I assume by the tread life ratings, that the Contis are a slightly different compound and have a better wear factor. Also, there is a difference in the tread pattern. But, so far, there is a distinct difference.
This was just a genuine question.
"Actually, this is better advice in a round about way. Most dealers don't have a road force balancer. They aren't in the tire business, and these are expensive machines. But even the most expensive machine can only fix the correctly diagnosed problem. If it's cupping, that's a suspension component issue, and the dealer should be attending to this, but if its feathering then the tire pros should be able to dial that in as well as any dealer, provided they are good also. Keep in mind that the IS models don't even have any camber adjustments available stock. Although I think the AWD does for some reason. "
I am not a tire expert by any stretch, but I have had lots experience with tires (40+ years). I have had tires "road force balanced" and the balancer will not cure an out of round tire. In fact, it's usually been a tire tech or store manager, trying to convince me that somehow their fancy tire balancer is going to magically balance my tire. Road force balancing will NOT cure a problem with a tire or wheel that is defective or its dimensions are outside of the physical requirements for simply balancing the tire on the wheel. It certainly doesn't take an MIT graduate to look at the tire and the wheel while it's spinning on a typical balancer to see if the tire and wheel are out of round or abnormal movement that would cause a problem.
You can balance a square tire while its' spinning. So even if you put an oval tire on a balancer, I can spin balance that thing well back into spec. The spin balancer has no clue nor does it care what shape the tire is. You would have a ridiculuos amount of weights on the rim, but the spin balancer would read it's good.
In my experience, cupping is NOT just a suspension component issue. I've had multiple sets of front tires on my trucks start to cup after 7K or 10K miles. In that case, the cupping is caused by the tread lugs. The spacing between the lugs allows them to "squirm". That condition of tread wear apears to be fairly normal for larger lug truck type tires. And yes, the suspension system and wheel alignment were fine and the tires were religiously rotated and rebalanced every 7K miles. I am anal about vibrations.
We are talking about vehicle geometry here. I really don't want to get all technical and start importing diagrams and charts, but trucks that expereince tire cupping are being overloaded or thier suspension is designed for heavy loads and they aren't carrying any. So the suspension system isn't loaded enouph and causing the cupping. You can't have both worlds. Ford for years used the twin I-beam suspension that was notoriuos for cupping tires, and didn't have a very good turning radius, but it was a very strong suspension set up. The "squirming" on the tread blocks that your referring to is a result , not a cause. They squirm because the suspension is flexing in and out of spec or under and overload.
If the IS250 does not have a camber adjustment, then perhaps the design is bad. Does that mean that the Toyota engineers figured out that there wont' be a problem with wheel alignment, and that camber adjustments to their genuis suspension design won't be necessary? No camber adjust is fairly common on newer front wheel drive cars, but I find it interesting that the rear wheel drive IS250 does not.
I don't really understand this desicion much either to be honest. My only guess here is in the persuit of trying to be more and more maintenance free, they decided most people don't adjust thier camber anyway, so why make it adjustable? It's just one more thing to maintain then.
Please explain what you mean by "but if its feathering then the tire pros should be able to dial that in as well as any dealer, provided they are good also". How does a tire pro shop "dial in" a feathered tire?
Tire feathering is from a bad toe in/out setting. easily adjusted on the rack when they are doing the alignment.
There a millions and millions of tires put on vehicles that work perfectly normal that never see a "road force balancer".
Because those larger sidewalls hide this issue much better. Lower the profile like we have, and you have to be alot more exact.[/quote]
What does rotating a tire on its wheel 180 degrees do?
[code] Road force balancing measures the roundness of the tire, by measuring the amount of pressure where the contact patch actually is. Most all rims are not perfectly round to begin with, and have some movement in them straight from the factory. So in essence and for the sake of keeping this relatively short, it measures the amount of movement in the rim, then tells the tech to rotate the heavier portion of the tire to the opposite side of where the rim is out of round the most to create a rounder, more even contact patch.[/quote]
"For most consumers, it's not a big deal to them, so alot of tire shops get away with this. Frequently. I only do business with tire shops that do road force balancing. It's more work for them, as they have to mount the tire, spin it up and measure it, then in some cases, stop, dismount the tire and rotate it on the rim 180 degrees, then remount it, and balance it from there. But I'm much more involved than most I would venture to guess. "
Most consumers.... What's "not a big deal to them"??
The laws of physics are fairly straight forward when it comes to balancing a tire. Although the dynamics are different when the tire is rotating down the road with a load, it's obvious that if a quality, non-defective tire is balanced properly on a typical spin balancer, then 99.99% of the time it's going to work fine on the road. However, I can balance a tire the shape of a football on a spin balancer, but obviously it's not going to be smooth on the road. Bent or out concentric wheels/rims and out of round tires can induce a vibration and cause tire tread to cup, regardless of how tight and perfect the suspension components are. That's MY experience.
I have a gut feeling that the multiple post regarding abnormal tire wear issues that have surfaced here, and with my own experience with my wife's IS250, that 1) The choice of factory tires by Lexus was stupid. 2) The suspension system on the car is way too loose or a *BLEEP* poor design.
Again, the IS250 as a top brand luxury 4-door sedan at $38,000 US dollars, should NOT have tires that wear out in 10,000 miles!!... camber adjustment or no camber adjustment!!
[code] Sometimes you surprise me Randy. I would think you should be more familiar with suspension geometry's as you have racing in your background. Every car manufacturer has the exact same desicions they have to make, and no matter what that desicion is, there are a bunch of haters complaining and sniveling over it. The facts are, a suspension system that places the tire in a more vertical postion, ie, gets great even tread wear, corners crappy and is unstable at higher speeds. That's a law of nature that science can't overcome. A tire that is more cambered, has alot more stability at high speed, and offers alot more traction in cornering, but at the expense of localized tread wear. Every car ever built faces these same issues. so when they decide tread wear is more important, then you would be complaining that the car doesn't corner very well, understeers all over the place, and won't track, or want to stay on the line you pick with the sterring wheel. You know how some cars feel like they "wander" going down the road all the time? And your forced to constantly correct the steering? they probably get great tire wear. Just look at all those 1980's-1990's cars that get great tire wear, but all performed very poorly. Now we are starting to see some real performance for a change. And when they decide performance is the higher priority, then they have to decide how much tire and suspension wear they are willing to sacfrice to achieve the level of performance they are looking for. 15-20k miles on performance tires is common across the board. Maybe you should be driving a Volvo?
That's just my worthless opinion.