cite please?
I can tell you that if I returned a car back to the owner pulling to the right, they would make me do the job over again. Furthermore they would be right, the car should not pull or drift either right or left when on a flat road with a normal amount of crown.
My bad Dutchboy208 – badmana asked the question I will find an answer to.
Gotta disagree with that. Whether it uses a rack and pinion or a steering gearbox, the system is not designed to pull. Perhaps the confusion is that virtually all roads are crowned (higher in the center) to ensure rain drainage; a car in perfect alignment will drift to the right because of this slight downhill slope to the right. This would be to the left if driving on the left side of center, as in England and Japan.
In the days when all cars had adjustable caster, it was common to adjust the alignment so that there was a bit more positive caster on the right side. This would cause a slight drift to the left (by adjustment, not by design) to counteract the drift caused by road crown, often resulting in a car that would go perfectly (or nearly so) straight ahead with hands off the wheel. Since caster doesn’t affect tread wear patterns, this approach worked well.
Nowadays a lot of cars don’t provide for caster adjustment. Camber adjustment can be made a bit more negative on the right to offset the crown effect, but since caster does affect tread wear, there are limitations on doing this. And some cars don’t even provide for camber adjustment.
Some rack and pinion designs tend to seek the center position of the rack with hands off the wheel. They are thus sensitive to toe adjustment, and will drift or pull if the toe-in is not equal left and right. All cars have adjustable toe.
Hmm… OEM tires aren’t necessarily the same ones you can go buy at the local Discount Tire, even though they may be the same brand and model. There are scads of comments and anecdotes about them wearing fast if you look on the web.
That aside, front and rear tires will have different wear patterns- that’s why they recommend rotation every 4000-8000 miles(depends on manufacturer and vehicle). This evens out the wear, and will make tires last longer due to more even wearing.
9000 miles without rotation could easily be enough for abnormal wear if the vehicle has an unusual or aggressive suspension or a 4x4. Plus, 9000 miles is about 1/4 of the way through the tire lifetime for an average pickup tire, so seeing some wear at this point is probably unusual.
How worn are they? I’d guess at 9000 miles, you could just rotate them and let them even out, unless they’re particularly short-wearing OEM models.
I take this back. It was something my dad had always told me, and I read an interview with Butzi Porsche (designer of the original 911) where he mentioned how the unequal left/right weight distribution of the engine caused the car to pull slightly, which was great because it meant they didn’t have to set the steering off center (for the reason I mentioned). I reread it this morning- turns out he was talking about the 935, which was a competition-only model, not about roadgoing versions.