Mixing tires on 99 Boxster

[kls]

"Kls, you need new rear tires...soon. When new, our tires are about 10/32's. Tires are considered "worn out" at about the 3/32nd mark."


Thanks bmussatti, it shall be done. Would you match the Michelins on the front, or just get a new set? Also, does the tire pressure sound OK?

Originally Posted by kls

"Kls, you need new rear tires...soon. When new, our tires are about 10/32's. Tires are considered "worn out" at about the 3/32nd mark."


Thanks bmussatti, it shall be done. Would you match the Michelins on the front, or just get a new set? Also, does the tire pressure sound OK?

Kls, Michelins are great tires...$$$$...but good. I would just replace the rears with a set that matches the fronts. Your tire pressures appear fine.

[jci-joe]

What are your thoughts on replacing the rear tires with new SO3's to match the front. Are there any concerns with the differing tread depths? That way, they would all match just not be the same age. The age of the front tires is 4 years also.

[MNBoxster]

Originally Posted by jci-joe

What are your thoughts on replacing the rear tires with new SO3's to match the front. Are there any concerns with the differing tread depths? That way, they would all match just not be the same age. The age of the front tires is 4 years also.

Hi,

If it were me, I think that's the best plan if not doing a complete set. One thing to bear in mind too is that many tires, especially Performance Tires often do not wear linearly, that is the Tire may have only gone from 10/32s to 7/32s in 10k mi., but be all in by 15k mi. - just something to be aware of and keep an eye out for...

Happy Motoring!... Jim'99

[David N.]

I'm assuming that mixing tires between front and rear axles is an easy way to seriously make your car oversteer/understeer-happy at the limit? Especially with a higher stickiness performance tire?

Its pretty common that the rear tires will wear faster than the fronts, I'm curious how much wear alone decreases a tire's stickiness. Could wear alone make as much difference as a different tire between the axles?

-David

[MNBoxster]

Originally Posted by David N.

I'm assuming that mixing tires between front and rear axles is an easy way to seriously make your car oversteer/understeer-happy at the limit? Especially with a higher stickiness performance tire?

Its pretty common that the rear tires will wear faster than the fronts, I'm curious how much wear alone decreases a tire's stickiness. Could wear alone make as much difference as a different tire between the axles?

-David

Hi,

You're correct. The handling can be affected, the effect can be magnified at speed or high g maneuvering. You're also correct that Tires lose grip as a product of age. The compounds used in Modern Tires will harden with age resulting in greater slippage, irrespective of Tread Depth...

Happy Motoring!... Jim'99

[racer_d]

Originally Posted by MNBoxster

Hi,

You're correct. The handling can be affected, the effect can be magnified at speed or high g maneuvering. You're also correct that Tires lose grip as a product of age. The compounds used in Modern Tires will harden with age resulting in greater slippage, irrespective of Tread Depth...

Happy Motoring!... Jim'99

um... yes and no

A DOT Competition tire like the Toyo RA-1 actually improves its DRY grip as the tread blocks wear down. Conversely, its wet weather performance diminishes due to smaller areas to dissipate the water.

While it is not recommended to run two different types of tires on a car, one should at minimum make sure the front wheels match each other and the rear wheels match each other.

It would also help to make sure the tires were of like compound and construction. ie.. a tire with a Treadwear rating of 300 and heat rating of AA will wear differently than a tires whose ratings are 100 and A, respectively.

Be smart about it. Boxsters (and Porsches in general) were not CHEAP to buy OR Maintain.

Also, expect rears to wear out about in about 1/2 of the time it takes to wear out the fronts. After all, that is where the weight and power go to!