Max Tread Differential For Tires?

[pauljcl]

I have an AWD RX350 with about 9000 miles. I have not 'rotated' tires yet, will do so in about 1000 miles. But, whereas on previous cars (used or new) the spare was either a space-saver spare or a used tire, in my case - now - the spare is a new tire. [i have always resisted rotating tires every 5000 miles because, if alignment is OK, in my experience, there is no need to do so except at 1/2 life or so of the tires; and if alignment is not OK - well - better to see it and correct it].

In this particular case, my choice will be to include (or not) the spare tire in the 'rotation'. In favour is the equalized use of all tires (and longer overall life), against is the possible impact on the traction control. Audi recommends against using any one tire that has more than 3/32" tread above the others in their Quattro (AWD) system; on my BMW, I had to replace one tire and it had about 3/32" more than the one on the other side - I happen to run them in the rear - and, as they wear, the traction control signal flashes sometimes (I found out that, by reducing pressure slightly - +/-1.5 psi - in the tire with the most tread, the problem is eliminated).... So, now, I understand why Lexus recommends rotation every 5000 miles - and including the spare!

The question is: Does anyone know the tolerance of wear between tires on the AWD RX350 that Lexus (or the traction system) allow? Is it, like Audi, 3/32", or less or more? And does anyone have an idea of how much tread is consumed over 10K miles on average - I have Michelin Energy 18" OEM tires.

Thanks!

[RX in NC]

As poor as the all-wheel-drive system is in the RX series, I doubt if the vehicle will be sensitive enough to detect the difference in treadwear if you decide to work your spare into the rotation. Be aware that by not rotating your tires often enough, you are shortening their lifespan regardless of how evenly you believe they are wearing. Front tires always suffer more edgewear at the side blocks as a result of constant steering and turning requirements regardless of psi or alignment specs. Rotate your tires more often to help balance out this effect. A good rule of thumb is to rotate your tires at every oil & filter change....

[pauljcl]

As poor as the all-wheel-drive system is in the RX series, I doubt if the vehicle will be sensitive enough to detect the difference in treadwear if you decide to work your spare into the rotation. Be aware that by not rotating your tires often enough, you are shortening their lifespan regardless of how evenly you believe they are wearing. Front tires always suffer more edgewear at the side blocks as a result of constant steering and turning requirements regardless of psi or alignment specs. Rotate your tires more often to help balance out this effect. A good rule of thumb is to rotate your tires at every oil & filter change....

Tkx. for your comments. I'll get Lexus to rotate including the spare, and, in the event of a problem, either revert to all used tires or else reduce the pressure very slightly in the newer one. It will be a bit of fight with Lexus: they never want to include the spare.....

[The G Man]

As poor as the all-wheel-drive system is in the RX series, I doubt if the vehicle will be sensitive enough to detect the difference in treadwear if you decide to work your spare into the rotation. Be aware that by not rotating your tires often enough, you are shortening their lifespan regardless of how evenly you believe they are wearing. Front tires always suffer more edgewear at the side blocks as a result of constant steering and turning requirements regardless of psi or alignment specs. Rotate your tires more often to help balance out this effect. A good rule of thumb is to rotate your tires at every oil & filter change....

Tkx. for your comments. I'll get Lexus to rotate including the spare, and, in the event of a problem, either revert to all used tires or else reduce the pressure very slightly in the newer one. It will be a bit of fight with Lexus: they never want to include the spare.....

The Lexus stability program is pretty conservative, if the spare tire actually have more than 3/32" threads than the other one, I would not include it in the rotation.

Personally, I think rotating tires doesnt make sense financially unless you do it yourself. Each tire rotation cost about $40 at the dealer. So rotating every 5000 miles up to 50000 miles would cost $800. Say if by rotating your tires, you are actually getting 50000 miles out of your tires instead of 40000 miles. Thats is an extra 25% life span. A typical set of tires for the RX cost about $800 to installed and balance, so by rotating your tires every 5000 miles, you are spending $800 to save $200.

[pauljcl]

As poor as the all-wheel-drive system is in the RX series, I doubt if the vehicle will be sensitive enough to detect the difference in treadwear if you decide to work your spare into the rotation. Be aware that by not rotating your tires often enough, you are shortening their lifespan regardless of how evenly you believe they are wearing. Front tires always suffer more edgewear at the side blocks as a result of constant steering and turning requirements regardless of psi or alignment specs. Rotate your tires more often to help balance out this effect. A good rule of thumb is to rotate your tires at every oil & filter change....

Tkx. for your comments. I'll get Lexus to rotate including the spare, and, in the event of a problem, either revert to all used tires or else reduce the pressure very slightly in the newer one. It will be a bit of fight with Lexus: they never want to include the spare.....

The Lexus stability program is pretty conservative, if the spare tire actually have more than 3/32" threads than the other one, I would not include it in the rotation.

Personally, I think rotating tires doesnt make sense financially unless you do it yourself. Each tire rotation cost about $40 at the dealer. So rotating every 5000 miles up to 50000 miles would cost $800. Say if by rotating your tires, you are actually getting 50000 miles out of your tires instead of 40000 miles. Thats is an extra 25% life span. A typical set of tires for the RX cost about $800 to installed and balance, so by rotating your tires every 5000 miles, you are spending $800 to save $200.

I've been on your side of the argument. I usually rotate once (about midlife, but anything from 1/3 to 1/2 life should be fine), and rotation consists simply of moving fronts to rear and vice-versa, without switching sides. [ I am from the 'old school', where it was deemed to weaken the steel radial belts if they were 'switched' sides and thus have torque applied in the opposite direction]. Now I have the issue of the spare.. which is new and also - I understand - replaced by another model (Mich. Primacy instead of Energy). I guess I'll just keep the spare, then, and keep the used tires on the ground. This rotation will be at Lexus' expense, since I deferred the 'free' oil and rotation.... By the way, tire shops here charge $5.- per tire for rotation, but inflation (pun intended) may change that.

[RX in NC]

I have rotated my own tires on all of our vehicles for more than 30 years. I don't pay for services that I can easily do myself right here in my driveway in less than 30 minutes. It's the standard final step in my oil & filter change policy.

Paying your dealer to rotate your tires is insane given dealer-inflated prices for any type of service. Some tire stores (such as Discount Tire) include lifetime rotations and nail repairs in their prices. And I've always been able to negotiate with Discount Tire to match or beat tirerack.com's prices. So if you are uncomfortable doing your own rotations, this is an easy solution.