Tire/ Wheel selection |
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RLM
Baja Godfather Joined: Nov/15/2012 Location: Hamilton, ON Status: Offline Points: 1258 |
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Posted: Sep/13/2018 at 7:06am |
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This statement was where I was trying to steer the conversation, Just didn't think it would need to be this spelled out.
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McMaster Baja Racing (09-Dec 2015)
Team Captain 2012-2015 Suspension Lead 2015-2016 All spoonfeed PM requests will be billed at $10 USD per reply, payable via paypal. |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Thank you
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Thank you for your explanations but you still have not answered my question.
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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Now I get what you want to ask.
To be honest, whether to consider the static or rolling friction coefficient is a pretty basic concept, I would suggest you rethink this and try to imagine the car as a brick or a brick with wheels. Coming to the second part, the air drag is an additional resistance the car faces, so it is a separate effect. The last part, regarding the rolling resistance, I think needs some clarification. The rolling resistance is purely a resistance offered by the viscoelastic nature of the tyre rubber to a freely rolling tyre. This is coming solely from your tyre and hence is also a separate effect.
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Yes. For example: F_static = u*N, where (u=0.4) static friction coefficient and (N=310kg*9.81) normal force. Therefore F_static = 0.4*310*9.81 = 3041.1N. And F_rolling = u*N, where (u=0.02) rolling resistance coefficient and (N=310kg*9.81) normal force. Therefore F_rolling = 0.02*310*9.81 = 60.822N.
Remember there is also an air drag resistance force that I have to add on these two forces. My question again, do I add Air drag resistance force with rolling resistance force or Air drag resistance force with static friction resistance force or I have to add all three resistance forces in order to get the total resistance force for an accelerating Baja from rest on a flat level track?? |
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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Are these calculations to determine the resistance to your car? Then neither.
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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I hear u but my question is, which friction must I use in my calculations between static friction resistance and rolling friction resistance?
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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This is definitely not one of the reasons why you have a decreased speed range. I do not understand how you would use this and calculate the resistance forces. Friction is paramount for grip without which you would have 100% slip condition i.e. the tyre with a certain angular velocity but with no forward speed. My suggestion would be to reinvestigate the losses in your transmission.
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RVCE BAJA: 2011-2015
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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There is no such thing as a rolling resistance friction. It is either expressed as a moment or a force (not preferred). The rolling resistance moment maybe one of the reasons for your decreased speed range but however I would only investigate this after going through other losses such as the transmission, air drag etc. I do not understand what you mean by the next highlighted statement.
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Static friction between the Baja Tires and the surface or road. Remember the rolling friction occurs between the tires and the surface also.
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RLM
Baja Godfather Joined: Nov/15/2012 Location: Hamilton, ON Status: Offline Points: 1258 |
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The static friction of what?
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McMaster Baja Racing (09-Dec 2015)
Team Captain 2012-2015 Suspension Lead 2015-2016 All spoonfeed PM requests will be billed at $10 USD per reply, payable via paypal. |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Hi
I am working on the Mini Baja from South Africa. The total weight of the mini Baja including the weight of the baja is 310Kg. My aim is to archive the maximum velocity between the range of 50km/h-60km/h.But I only managed to archive 44km/h by calculations. My question is, when I calculate the resistance forces, should I consider both Static friction and Rolling resistance friction? In my calculation I considered them both and I found that, the static friction has a very huge negative impact towards achieving my goal. Now I am not sure if I should take the static friction into account. |
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sujandinesh
Baja Godfather Joined: Dec/27/2013 Location: Enschede Status: Offline Points: 494 |
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I do not exactly know the typical values for rolling resistance of a Baja tyre but however, based on my experience, they must be in the range of 10N - 150N. Please keep in mind that rolling resistance is a function of the vertical force, inflation pressure and forward speed of the tyre and hence I have expressed it as a range.
You can experimentally determine your tyre's static friction coefficient by using a simple spring balance. This value would be realistic and it would also have more validity during your design evaluation and car's dynamic analysis.
Edited by sujandinesh - Jul/18/2018 at 3:58am |
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RVCE BAJA: 2011-2015
General Motors: 2015-2016 Tyre Testing - University Racing Eindhoven: 2016-2017 Tyre Dynamics - TASS International: 2017-2018 Tyre Engineer - Apollo Vredestein The Netherlands |
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Bantu
Bolt Sorter Joined: Mar/06/2018 Location: Port Elizabeth Status: Offline Points: 30 |
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Does anyone knows what are the typical values of the rolling resistance,and static friction coefficient of the mini Baja tire running on the tared track/road?
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Soccerdan7
Organizer Joined: Sep/22/2010 Location: CA Status: Offline Points: 780 |
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We have used them for our rears for our last 3 competitions and the only flat we had was due to a massive impact that also dented our trailing link, bent the lower camber link pretty bad and sheared the driveshaft...
They are a great lightweight rear tire.
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Danny
Cornell (fall'07 - spring'12) Former Captain / MEng / that guy with all the carbon 10 races, 7 top ten's, 2 overall wins |
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ballast
Bolt Sorter Joined: Sep/30/2012 Status: Offline Points: 28 |
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anyone who has used carlisle at489 2*ply tires please share your experience . I personally think that 2ply is more prone to punctures or cuts. But my doubt is that will it get punctured even under normal conditions or only under harsh conditions. Any information will be appreciated. thankyou.
Edited by ballast - Sep/30/2012 at 4:23am |
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jacking with the screw
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Just in case any one is interested.
They cost $140.
Edited by Akron 1998 to 2004 - Mar/18/2011 at 12:20pm |
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CLReedy21
Baja Godfather Joined: Nov/30/2008 Location: Marysville, OH Status: Offline Points: 736 |
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You're probably gonna find that one under the "call" section.
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-Chris Reedy
TTU Alumni Fourwheeler Drawer "Quick with the hammer, slow with the brain." |
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Where do you get your Douglas wheels from? I'll need to buy some soon. I need this:
4/4 10X6 1.0 + 5.0 0.190 (red label?)
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Greenreed1936
Bolt Sorter Joined: Aug/31/2009 Location: Rapid City Status: Offline Points: 24 |
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Well thats true. You were driving |
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SDSMT BAJA SAE
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SDTech
Milling Master Joined: May/13/2009 Location: Rapid City, SD Status: Offline Points: 68 |
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To be fair, that wasn't really the fault of the wheel... |
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SDSMT Baja SAE
Car #'s 4 & 6 - Oregon Car # 14 - Wisconsin #4 & #79 - Western Washington 2010-2011 SDSM&T Team Lead |
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Greenreed1936
Bolt Sorter Joined: Aug/31/2009 Location: Rapid City Status: Offline Points: 24 |
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We have run Keizer wheels for the last 5 or so years and just now had one destroy itself at Michigan Tech's Winter Comp.
They hold up to the abuse quite well. A little spendy but perform very well. |
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SDSMT BAJA SAE
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dillon_b12
Baja Godfather Joined: Nov/15/2008 Status: Offline Points: 781 |
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Douglas wheels can be had in 4+1 as well as the standard 3+2 offset. I e-mailed Keizer near the end of '08 for some pricing so I'm not sure how current this is:
Current pricing for Douglas wheels: 10x5 Wheel 3+2 Offset 4/156 Bolt Pattern (This is a Yamaha Raptor wheel.) Blue Label(.125): $58.00 Black Label(.160): $68.00 Red Label(.190): $77.00
Edited by dillon_b12 - Mar/14/2011 at 6:26pm |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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You can backspace Douglas wheels 1, 2, 3, 4, 4.5 or 5 inches. The problems is if you got too much one way or the other you end up putting lots of stress on your wheel bearings.
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-Tom
Oregon State BajaSAE Team Captain |
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ErikHardy
Baja Godfather Joined: Apr/12/2010 Location: Hood, Flint, MI Status: Offline Points: 939 |
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I misread what he was talking about, I thought he had a flat lugnut and just needed a tapered end, my mistake.
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Douglas wheels are almost all spaced 3" in from the outside. Keizer will make you one spaced 0". That means your custom A-arms can be 3" longer, better angle on the ball joints, more travel, what ever you want to design, etc. Keizer makes nice spun metal race quad wheels. Never damaged one with a anti-dent ring. |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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Most tapered lugs are 37 degrees (I believe). You would need a pretty massive lock nut to put that sort of taper on it.
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-Tom
Oregon State BajaSAE Team Captain |
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ErikHardy
Baja Godfather Joined: Apr/12/2010 Location: Hood, Flint, MI Status: Offline Points: 939 |
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Along the lines of what tp said, would there be enough material to put the lugnut in the lathe and put a small taper on the end of it. |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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With the demands of todays racers, you can get a Douglas wheel in almost any backspacing that you can dream of. Not only that, but personally I don't know how much I'm going to trust a road wheels with what we do. I've seen our Formula team break wheels. Judging by how many wheels I've destroyed, Baja just demands something stronger. If you have a properly designed suspension, you can get a zero scrub radius with whatever wheel you choose. Like maybe something off the shelf. EDIT- didn't realize that Keizer makes quad wheels too. Thought it was just sprint car and road wheels.
Edited by tp - Mar/14/2011 at 3:45pm |
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-Tom
Oregon State BajaSAE Team Captain |
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Akron 1998 to 2004
Welding Master Thread Hijack Champion Joined: Jan/20/2011 Location: WA Status: Offline Points: 327 |
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Wheels: I'm guessing its because of price but I'm a bit surprised we were the only Baja team that seemed to us Keizer Wheels. They are heavily used in SAE Formula. If you can find a Douglas rim in the size you need, they're cheaper. But for a little more $ Keizer will make a rim in any bolt pattern, diameter, width, back spacing you want. You can get absolutely zero scrub radius with custom back spacing! Don't know what the current pricing is like but a custom rim with dent rings and mud cover cost about $120 back in the day.
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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Using a normal nut when you need a tapered one would be inviting disaster. Your wheel would never be concentric. One option if you need tapered lock nuts is to make tapered washers and the use a normal lock nut. Wouldn't be too hard to drill out a tapered nut and cut it down to turn it into a tapered washer. |
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-Tom
Oregon State BajaSAE Team Captain |
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tech.tmr11
Bolt Sorter Joined: Dec/14/2010 Location: Manipal Status: Offline Points: 23 |
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last time we used locknuts....no problem with that....
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TEAM MANIPAL RACING
INDIA |
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rohanlakhotia46
Milling Master Joined: Sep/09/2010 Location: Vellore, INDIA Status: Offline Points: 49 |
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our team has been facing a few problems regarding the wheel's nut. Apparently the nut used here is tapered and is the one generally used in normal passenger cars in India.
The diameter of the hole on the Hub is slightly smaller than the corresponding hole of the rim. Hence a Tapered Nut has been used for the same to provide a proper fastening system, as shown in the pictures. However we don't have tapered lock nuts available in India. I wanted to know if we are allowed to loctite over there or is there any other solution? We are also thinking of using a cotter pin after drilling through holes in the bolt and nut. |
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Rohan Lakhotia
`The 46 Doctor` TEAM JAABAZ Vellore Institute Of Technology vellore,t.n., INDIA Car #42 (kansas) |
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collinskl1
Baja Godfather Joined: Jan/21/2009 Location: Saginaw, MI Status: Offline Points: 1056 |
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I always struggled with the fact that we had to predict the conditions and track style (for the most part) months in advance. I guess you could take multiple sets and make a final choice before tech inspection on site... This is why I always defaulted to standard mudlites; because they're light, aggressive, great in soupy conditions, and as good as anything (barring maybe Terras or other farm implement tread) in water.
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Kyle Collins
Lipscomb University Alumni 2x Project Manager Nexteer Automotive Product Engineer, Electronic Power Steering ... and the 8th simple machine: a bigger hammer. |
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Red_Beard
Organizer Joined: May/14/2009 Location: Bellingham, WA Status: Offline Points: 269 |
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Yes I have and got some very good results from it. I found that there are certain types of soils and soil conditions that lend themselves to extremely grooved tires, and others that lend themselves to standard tread patterns. |
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SDSM&T 09-10 Team Lead
2nd & 9th Baja West Project Engineer Matrix Service - Bellingham, WA |
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CLReedy21
Baja Godfather Joined: Nov/30/2008 Location: Marysville, OH Status: Offline Points: 736 |
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We used to groove the old 27lb terras, but we've moved past that a little.
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-Chris Reedy
TTU Alumni Fourwheeler Drawer "Quick with the hammer, slow with the brain." |
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collinskl1
Baja Godfather Joined: Jan/21/2009 Location: Saginaw, MI Status: Offline Points: 1056 |
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Which is why they really aren't a good idea. They suck off road for anything but mud because of how stiff they are, and they're too aggressive for on road use... It would be better to have two sets of tires.
Annnnyways, back on topic: Has anyone tuned tires? Like taking a grooving iron to a set to change the tread pattern?
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Kyle Collins
Lipscomb University Alumni 2x Project Manager Nexteer Automotive Product Engineer, Electronic Power Steering ... and the 8th simple machine: a bigger hammer. |
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Red_Beard
Organizer Joined: May/14/2009 Location: Bellingham, WA Status: Offline Points: 269 |
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They suck ass... I would rather go through 10 sets of bias swampers before buying another set of those piles of crap. |
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SDSM&T 09-10 Team Lead
2nd & 9th Baja West Project Engineer Matrix Service - Bellingham, WA |
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p.lewis
Welding Master Joined: Oct/05/2009 Location: Greater Detroit Status: Offline Points: 296 |
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Thanks for the link!
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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Yeah yeah I know . But people also use swampers for street rigs. |
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-Tom
Oregon State BajaSAE Team Captain |
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collinskl1
Baja Godfather Joined: Jan/21/2009 Location: Saginaw, MI Status: Offline Points: 1056 |
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They make radial swampers too...
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Kyle Collins
Lipscomb University Alumni 2x Project Manager Nexteer Automotive Product Engineer, Electronic Power Steering ... and the 8th simple machine: a bigger hammer. |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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Rather than write up something nice and long about bias-ply and radials, this guy here does a pretty good job of describing the differences:
http://www.mud-throwers.com/bias_vs_radial_tires Tires like the BF Goodrich Baja TA are of radial construction whereas something like an Interco TSL is a bias-ply. Two different uses- two different tires. |
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-Tom
Oregon State BajaSAE Team Captain |
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collinskl1
Baja Godfather Joined: Jan/21/2009 Location: Saginaw, MI Status: Offline Points: 1056 |
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Well my ignorance can be explained by my lack of insight into ATV stuff until my baja involvement
Without testing this is all speculation, but I'm not sure I would want to lose the internal stiffness of a higher ply tire. As mentioned in the "bottomed out" thread by Chris, our tires flex A LOT on impacts. I like my wheels to be as round as possible! I also like having predictable handling afforded by lateral stiffness of the sidewall and only relying on the tread "un-side-bite-ness" to be able to slide around a corner rather than the sidewall rolling over so the contact patch is no longer located on the center of the tread but the edge lugs.
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Kyle Collins
Lipscomb University Alumni 2x Project Manager Nexteer Automotive Product Engineer, Electronic Power Steering ... and the 8th simple machine: a bigger hammer. |
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dillon_b12
Baja Godfather Joined: Nov/15/2008 Status: Offline Points: 781 |
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Actually, until recently, almost all ATV tires were bias-ply.
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collinskl1
Baja Godfather Joined: Jan/21/2009 Location: Saginaw, MI Status: Offline Points: 1056 |
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I don't know much about the ATV world, but are there really many bias ply tires that small? I know in the truck/rock crawling world bias tires are sometimes more desireable because they are not as stiff and can conform to obstacles better. I'm not certain if that would be a good thing at high(er) speeds and terrains baja cars encounter. |
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Kyle Collins
Lipscomb University Alumni 2x Project Manager Nexteer Automotive Product Engineer, Electronic Power Steering ... and the 8th simple machine: a bigger hammer. |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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You're just trying to make me work.
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-Tom
Oregon State BajaSAE Team Captain |
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CLReedy21
Baja Godfather Joined: Nov/30/2008 Location: Marysville, OH Status: Offline Points: 736 |
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Anybody want to throw radial vs bias ply into the mix?
Edited by CLReedy21 - Dec/15/2010 at 5:21pm |
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-Chris Reedy
TTU Alumni Fourwheeler Drawer "Quick with the hammer, slow with the brain." |
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tp
Welding Master Joined: Mar/31/2009 Location: Corvallis, OR Status: Offline Points: 348 |
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Now we're going from Tire 101 to Tire 202. The weight difference in ply is going to depend on the construction of the tire. A little brief on tire construction: a ply is the layer of fabric that is laid into the rubber while the tire is being molded. So in a lot of cases more plies are heavier. But as pointed out the Maxxis Razr2 is a 6 ply and doesnt weigh much more than a 2 ply Carlisle. Just depends on what is used to construct each ply. A lot of the new high performance tires are using kevlar. I'm not sure about your question on increasing PSI. The number of plies really isn't going to determine the side bite of a tire. Bumping up the pressure will increase how stiff a tire is. This can help protect the wheel lip, but there are a whole other set of things that you have to worry about by doing that. It will change the size of your contact patch which will change how your car will handle. Also increasing the PSI will put more force on the bead meaning you're more likely to blow it off.
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-Tom
Oregon State BajaSAE Team Captain |
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collinskl1
Baja Godfather Joined: Jan/21/2009 Location: Saginaw, MI Status: Offline Points: 1056 |
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Dillon is absolutely correct here. It's the same concept as when you're in the air you aren't going faster, if your tires are spinning you aren't getting full traction, you can't win the race on the first lap but you sure can lose it, etc. I'll sacrifice a little weight for a lot of robustness any day of the week. In my opinion wheels and tires are a great place to shave weight, but there is a fine line to be tread (no pun intended).
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Kyle Collins
Lipscomb University Alumni 2x Project Manager Nexteer Automotive Product Engineer, Electronic Power Steering ... and the 8th simple machine: a bigger hammer. |
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