Originally Posted by
Hawk6
I'll be the first "not so expert" to reply:
My understanding of the reason for "Double stuffing" is to get a bit more "gearing" (actually a bit more roll-out). Double stuffing gives you a slightly larger diameter tire, so the roll-out is slightly higher. I haven't done the math, and I doubt it makes this big of a difference, but it may be like running a 21 tooth pinion instead of a 20.
So... there would be no reason to double stuff the free-wheeling rear tires .
Does that make sense?
Actually, I think the double stuffing is not for more rollout.
With the front drive mini, there is a forward weight bias. The 60 D tires have a fairly large sidewall height, and that sidewall is fairly soft, expecially on the S grip radials and A compound slicks. What double stuffing does is give you a full tire, one in which the sidewall will not flex or collapse (fold over) during cornering. Less flex or collapse means that the car will scrub off less speed during corners - keeps the corner speed up. It also will react faster in back to back steering transitions (chicanes).
If you watch a mini in a corner and it seems to snap the back end around unexpectedly, one thing to observe is whether the front tire sidewall is "folding over", digging in the front outside tire in the turn, which causes the inside rear tire to have less weight or even lift, and thus the spin out.
If you have the combination of a front tire folding over and too little shock suspension travel, you get a combination that can lead to snap roll overs in high traction situations like carpet.
The reason I have not found double stuffing the rears to be helpful is that the rear end of a mini is so light compared to the front, this "folding over" effect of the tire sidewall is minimal - thus no need to double stuff the rear tires.