Tires spin on rims???????

[Dan Cordon]

> This is the topic next to gas prices on Rennlist.
> 
> How often has this really happened?  Anyone experience it?
> .........Having the rims and tires shift position to go out of balance?
> 
> Could crazy grip and deceleration do this?
> Hmmmmmmmm. - Scott by BOSTON

I and some friends have experienced this. I occasionally go off-roading 
with my 69 FJ40 Land Cruiser. It runs 39" tall tires, so the distance 
from tire to rim is *much* larger than a car. And to make things better, 
we usually run very low air pressure (~2-3 psi for my combo) on the 
trails too. All this leads to a combination where the tire can slip.

But ironically enough, I have only experienced this about two times. 
Both were from hard braking events though.

And in drag racing my 70 Mach I would spin the rear tire on the wheel 
(very slightly) when launching. But this was a gummy slick - also at low 
tire pressures.

With a small profile car tire, I imagine this would have to be a VERY 
sticky tire to slip under normal pressures. I haven't heard anything 
about this with road race tires though, and they're sticky and they 
brake hard.

-- 
Dan Cordon
Mechanical Engineer
University of Idaho - Engine Research Facility