UTV(ATV) Tire Pacejka "Magic" Coefficients

[gt6racer2]

Hi All,
We usually work with on-road vehicles, but have to do some work with a side/side type utility vehicle. Tires are 27*9-12 and 27*11-12 ITP 900 XCT. Initially analysis is on asphalt. (I have seen the papers regarding studies on dirt)
Our current work is largely comparative rather than absolute, so the time expense of getting a tire characterized is not justified.
We have the coefficients for a 235/70/R16 Truck tire as follows :
a0 = 1.52
a1 = -23.28
a2 = -1048
a3 = -1683
a4 = -8.16
a5 = -6.76E-04
a6 = -0.0445
a7 = 0.0125
a8 = 0
a9 = 0
a10 = -0.0383
a11 = 0
a12 = 0
a13 = 0.4072
a14 = -0.00464
a15 = -1.71E-04
a16 = -0.0854
a17 = -4.70E-05
First Q - can anyone help with better Coef for the UTV type of tire ?
If not, we were thinking to scale the lat load/slip slope factor using 0.6, expecting that the tire will be more compliant than the tire we have the coef for. Are there any better ideas ? Is 0.6 considered a reasonable estimate ?


Thanks.

 

[GregLocock]

Drive on a 30m circle on asphalt with your known tires. note SWA vs speed

Drive on a 30m circle on asphalt with new tire. note swa vs speed

drive on a 30m circle on gravel with new tire note swa vs speed



Cheers

Greg Locock


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[patprimmer]

Not my area so I might be way off, but I imagine that gravel surfaces vary greatly with sand/clay/stone qualities and mixes and geometry of stone/sand and wear and with moisture content.

Of course asphalt also varies but I imagine it's a lot easier to control and specify

Regards
Pat
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[GregLocock]

Sure. A good gravel road, freshly laid and then bedded down nicely for a month is not far off asphalt, subjectively. One rainstorm or a truck too many and you are down to 60% grip.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[gt6racer2]

Greg, Thanks for the idea - a quick experiment might be the best approach. I was hoping someone might have experience with these tires already - but it appears no luck..