Tire Rotation Question

[LCOX]

I just purchased a new set of tires for my older 77 911 that has the same size rims for front and rear thus the same size tires.

The tire guy told me to rotate them only front to rear on the same side of the car only to prevent damaging the internal steel belts in the tires but I've always heard of rotating tires front to back diagonally. Am I wrong here. L

[Andy911sc]

Depends on your tread pattern. If you have directionals, you can only rotate front to rear, but if not I don't see why you couldn't rotate back diagonally. I would.

[schumicat]

+1, if your tires are directional (and most good ones are) they will have a "rotation --->" mark on the sidewall.

[porwolf]

I heard that, even if tires are symmetrical, sides should not be switched because the rubber, after exposure to one direction, is set to that condition. Reversing the direction could damage the tire. I heard the long time ago. Does that make any sense?

[JAR0023]

I need to piggy back in here. I was coming to post a tire rotation question. First every car I own, in the owner's manual, indicates that you should cross two tires left to right when rotating. RWD cross rears to opposite front. FWD cross fronts to opposite back. As long as the tires aren't directional that's what I've done for years. I think the thought on not crossing dates back to bias plys.

So my piggyback question. Just s/w mechanic today who is completing PPI and prepping car for the drive across country. He calls me today and says that the car is pulling a little and that it needs an alignment. He also says the car needed an alignment 3500 miles ago when current owner purchased car. Tires are directional Toyo Proxes. Rears in good shape, fronts is great shape...except all four tires are wearing at a differential rate inside to outside. It appears car has excessive negative camber all around. He wants to unmount tires and swap them left for right, remount, balance and align the car. I don't know that I can find fault with this. Anyone think this will cause any issues?

-J

[Arne2]

Originally Posted by porwolf

I heard that, even if tires are symmetrical, sides should not be switched because the rubber, after exposure to one direction, is set to that condition. Reversing the direction could damage the tire. I heard the long time ago. Does that make any sense?

Speaking from 25 years in the tire industry (prior career), that was true long ago, but radials have improved much since then, and that is no longer true for today's tires.

Originally Posted by JAR0023

So my piggyback question. Just s/w mechanic today who is completing PPI and prepping car for the drive across country. He calls me today and says that the car is pulling a little and that it needs an alignment. He also says the car needed an alignment 3500 miles ago when current owner purchased car. Tires are directional Toyo Proxes. Rears in good shape, fronts is great shape...except all four tires are wearing at a differential rate inside to outside. It appears car has excessive negative camber all around. He wants to unmount tires and swap them left for right, remount, balance and align the car. I don't know that I can find fault with this. Anyone think this will cause any issues?

-J

No problems that I can see, except that the cost to dismount and balance the tires may not gain you all that much. Odd as it may seem, tires do develop a wear pattern, and will continue to wear that way (to a lesser degree, of course) even after the initial conditions are corrected. I'd weigh the cost of swapping sides to the cost for a new set of tires. If the swap will cost more than 20-25% of a set of new, the cost/benefit ratio is marginal.

[midnight911]

+1 with porwolf.

i've seen few - not one but few - slow leaks with those switched sides and direction. i once heard tires seat to wheels in one direction and do not want to get disturbed by changing rotational direction. this is a long time ago, so it may not apply to today's tire technology.

[JAR0023]

Thanks for the insight Arne. I have to call the shop first thing Monday but am inclined to give it a shot. Car has 245/45r16s on 9s on the rear. Currently a matched set of Toyos. With that size becomeing scarce I think I want stretch these if I can. I'll definately keep a close eye on the pressures. Plus this is part of a PPI so I don't have to bear the full cost.

-J

[LCOX]

Yes I'm sorry I forgot to mention that these are non directional tires. L