Tire Rotation Question

Pedal pads, carpet, brake linings, u-joints, etc. Lots of things could benefit from "rotation" but unlike tires, none of those things (except some pedal pads) are easily rotated and the cost of rotation would not be offset by the increased life. Also, tires, unlike many of the wear items, deform significantly by their very nature and that deformation can lead to wear patterns that are non-uniform and that become self-generating as the pattern sets in. That's why it is generally beneficial to rotate tires, especially if it's a free service. If you have to pay for the rotations then it sometimes makes sense not to bother rotating the tires as on some vehicles the cost of the rotations will be more then the life you gain. I've had cars where rotation was a complete waste of time and others where it was absolutely necessary due to how the tires would wear.

Other than in a similar scenario to the aging, deteriorating tires, kindly inform us all as to how pedal pads, carpets ... could possibly "benefit" or experience increased life from undergoing reseating or being subjected to a different wear pattern. If you believe such abject nonsense, you should seriously consider regular, scheduled engine disassembly to "rotate" similar parts.

You're not done. Now there's nothing on the rear...

u

Actually, on a Porsche 944, and I ASSume whatever VW the parts were lifted from (Thing?) one can get extra life out of the CV joints by swapping them end to end (they're symmetrical and use bolted flanges at each end) BTDT...

I believe that's the exception rather than the rule however... most axles I've seen with Rzeppa joints are not anything close to symmetrical...

nate

Most brake pedals in cars with automatics will wear mostly on the right lower corner. If they are symmetrical you can rotate the pad and extend the life. Same with the carpet in your house, you could move the wear pattern around by rotating the rectangular sections and in a VAN with a rectangular flat floor (admittedly rare these days) you could do the same. You can also swap the sun visors in most cars from side to side to equalize sun damage, many car seat covers are the same for the left and right sides and you could make the set last longer by swapping the driver and passenger seat and foam. You could even rotate light bulbs from high usage locations to low usage locations.

I not exactly a strong advocate of tire rotation. For some vehicles I've done it, for others not. I've had at least one vehicle where rotating tires always led to problems, a 1986 Sable - all the tire wore square, but the front wore much much faster. If you tried to even out wear byt rotating, the car invariably developed a pull to the right. After the second set, I quit rotating tires on this car. On my current Fusion, rotating the tires seems to have no detectable (by me at leat) negative consequecnes. And I managed to wear out all four original tires (OE Michelins) almost perfectly evenly.

My sister's experiences with the Jetta did not involve cheap tires, unless you think Michelins are cheap.

I tried to find some sort of study that quantified the effect on tire performance of swapping ties around between axle locations and couldn't find anything other that vauge statements. For sure BMW advises against it. The following is from an online BMW Owner's Guide:

"Swapping wheels between axles

"BMW advises against swapping wheels between the front and rear axles, even if all tires have the same size, as this could impair driving characteristics. If the tires are of mixed sizes, swapping wheels between the axles is not permissible."

They don't exactly clearly state what they mean by "impair driving characteristics." Have you seen any studies that quantify this impairment? Interestingly, Mercedes-Benz does recommend routine tire rotation (for vehicles that have the same size tires on front and rear axles and they'll do the first rotation for free). They do specify that tires should not be cross rotated, as does Volvo. It seems that Volvo used to recommend against routine tire routation (back when they built rear wheel drive cars). These days, Volvo also recommends routine tire rotation.

So it seems to me that most vehicle and tire manufacturers recommend routine rotation with the cavet that you cannot swap tires of different sizes between axles, and that several manufactuers don't recommend cross rotation in any case.

I have a hard time with the idea that most vehcile manufacturer's are recommending rotation as some sort of anti-lawsuit measure. Particualrly if you buy BMWs arguement that swapping wheels between axles might impair driving characteristics. It seems as likely to me that you might get sued for telling people to rotate tires as you might if you didn't tell them to. I suppose they might recommend it as a way to avoid fixing design or manufacturing flaws that lead to uneven tire wear, but it seems jsut as likely they are recommending it as a way to equalize wear on tires for cars that inherently wear the front tire faster.

The 1986 Sable I owned wore out the front tires more that twice as fast as the rear tires. If you didn't rotate the tires you were forever buying two tires. I always liked the idea of running four matched tires. My family had a 1978 Fiesta. When we bought it, the advice given was to not rotate the tires. The car had very small (12 inch wheels) tires and the fronts wore out evey 25 to 30k miles. The rear tires didn't appear to wear at all. When the car was 8 years old, I finally swapped the rears to the front becasue they were so old. I figured I'd get as much out of them as I could before they dry rotted. We were lucky for that car. It came with Michelin tires, and at least for the first 8 years tyou could buy the identical replacment tire, so we always had a closely matched set. These days it seems whenever I go to buy tires, the tire model I used to have is no longer available. I hate the idea of having different front and rear tires. Maybe this is a silly personal thing, but I rather wear all four tires out as close to the same as possible and buy four news ones. For my trucks, this doesn't seem to be a big deal. The fronts and rears mostly wear the same. Ditto for my Fusion (an AWD Fusion). But for my son's Mazda3, the front tires wear at a much faster rate. Same is true for the SO's RAV4, and my sister's old Civic. The SO is on her third set of two tires. Whenever she buys two new tires to repalce the worn out front ones, they insist on moving the rear tires to the front and putting the new tires on the rear. So she is constantly buying new tires, two at a time. She doesn't mind and she doesn't like to have the tires rotated. Do you think rotating four tires that are the same imparis the driving characteristics more than having front and rear tires that are not the same?

I think most people should just foolw theeir own counsel when it comes to tire rotation. If you don't have a strong opinion, then I'd suggest following the advice of the vehicle manufacturer, which in most cases means

5000 to 8000 mile rotations. Although Volvo had an interesting recommendation - they recommended doig the first rotation at 3000 miles, and then following that up with the longer interval.

Ed

no, not all michelins are cheap. most are excellent in fact. but, some are awful - rain force for example. those mxv's that came oem on interga's are another.

ed, this is one of those real basic things like you not finding many studies on how wheels work - it's obvious to anyone who has any form of observational ability. take a nice FLAT surface like some 3/4 ply. dust it with builders chalk, then roll your car across it. on inspection of the chalk marks on the tires, you'll see how much of each tread block actually contacts the surface. then, rotate the tires so the sense changes, and repeat. you'll see a dramatic difference. since traction with tires is a form of adhesion, not coulomb friction, and therefore proportional to contact area, it doesn't take a rocket surgeon to figure out that reducing the contact area by rotation reduces traction and thus your ability to keep the rubber side of the vehicle pointed down.

Two thoughts on this experiment:

1) Given that tires support the weight of the vehicle via a combination of air pressure operating over the contact patch and sidewall stiffness, shouldn't the contact patch be relatively constant? I can't see how rotating the tire significantly effected the sidewall stiffness and therefore you need approximately the same contact patch size to support the vehicle. I suppose the shape might change somewhat, but this seems like it would be a minor issue. 2) OK, so how exactly did rotating the tires change the contact patch in your experiment? Say I move the front tire to the rear. I suppose the actual load on the tire will be different, so the contact patch would change, but would it be different than the tire that was originally on the rear? Is the idea that the tire tread profile is now different? So if the tires are wearing relatively well, rotating should not be a big deal? So as long as you rotate before you develope significant wear patterns, then no problem? 3) How significant is this change? Is it really that significant?

Ed

for f*ck's sake ed, just /do/ it - you've shown countless times that you're useless in the abstract.

side wall? red herring. i said "each tread block". pay attention.

20-40%. now get off your ass and head on down to the building supply depot.