Un-even Tire Wear - Page 2

ProfessorPaddle · 05-22-2009, 10:57 AM

I talked to the ford dealership, and after being scolded for not rotating at the proper interval the did confirm what Greg said. That tire is the power tire and the amount of wear was in-line with the time it spent in the rear passenger side. Just had them rotated, the spare swapped out and I am ready to roll.

Sorry for ever doubting you Greg... but can you really blame me for wanting to be like Jeff Gordon...

**BroncoHauler** · 05-22-2009, 12:39 PM

I'd still like to know what a power tire is.

Herb

ProfessorPaddle · 05-22-2009, 03:38 PM

The tire that is active first. Apparently the rear passenger side is the first tire to spin off the rear diff when you hit the gas...

From the mechanics I thought it was equal distribution but apparently its not. ???

geoffff · 05-22-2009, 06:27 PM

Yes, the diff distributes the torque 100% evenly -- but the weight isn't equal, so the traction isn't equal, so the wheel with the least weight on it will break free first.

This could be because your passenger side is lighter on your van (as is the case with mine, by about 300 lbs), or because you tend to make sharp right turns under power (while jumping in to traffic or something) -- and so the van leans left lightening the right wheels even more.

I'm guessing here that it's some kind of additional occasional slipping that's wearing that right rear tire out faster.

-- Geoff

Greg In Austin · 05-23-2009, 01:23 PM

Geofff,

I am not sure about that 100% Evenly..... if that were the case we would have a hard time ever making a corner without skipping and chirping....

geoffff · 05-23-2009, 02:47 PM

The trick with an open differential is: it's the wheel torque (that is -- force), not the wheel speed that's distributed 100% evenly.

This is why your tires don't chirp around corners. And, why when one wheel starts slipping on ice (its wheel torque drops to near zero) the other wheel with good traction also stops pushing. Both wheel torques drop equally -- but the speed of the wheel slipping on the low-traction ice will much higher than the one on high-traction pavement.

-- Geoff

Greg In Austin · 05-23-2009, 02:58 PM

Thanks Geofff... I had read that wrong