Do you change all four of your tires?

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At work I do 2 at a time all the time.
And I had a weird one on a car at work that I actually did put a set of 4 onto...
Even though I put a set of 4 on this car (think it was a Pontiac G6) we had a problem with it pulling. We sent it for an alignment. Still pulled.
Swapped tires around (remember a set of 4 put on together, all same brand and model and size/ at least as marked) we ended up sending it to another alignment place, this one actually had access to a frame rack for pulling bent frames after a wreck. They solves it.
Seems that 1 of the 4 new tires was 1/4" shorter than the other 3.
And on that note when my son first got his ramcharger we went to a wal Mart and we looked at what they had. I pulled 3 different brands of 31-10.50-15 off the rack and set them side by side. A Firestone a Uniroyal, and (at the time, I don't think they sell these anymore) a "liberator". All 3 were supposed 31/10.50-15 as marked All 3 were different outside diameters. So much for conformity...
 
I pulled 3 different brands of 31-10.50-15 off the rack and set them side by side. A Firestone a Uniroyal, and (at the time, I don't think they sell these anymore) a "liberator". All 3 were supposed 31/10.50-15 as marked All 3 were different outside diameters. So much for conformity...
yeah, that's pretty common among manufacturers. especially with all terrain or more off road oriented tires. a 205 isn't always a 205 and with some of the race spec auto-x tires 205 is more of a designation on the sidewall only and not indicative of the actual width of the tire.
 
I find it interesting that the speed sensor can supposedly tell 1 tire turned 1 less rotaton in over a mile but the coupling of the AWD cant handle it. What am I missing?

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Depending on the fidelity on the speed sensor it could probably tell you a tiny fraction of a rotation difference over the course of a mile. Depends on the sensor.

As for what the AWD can handle, it depends completely on the differentials, viscous couplers, etc. If someone designed a viscous coupler that can't handle that difference in wheel diameters then that's the way it is. Obviously there's a tolerance for how much slip the differential or coupler can tolerate for how long before it overheats or burns up the diff or whatever, and that depends entirely on which one you've got. Probably shouldn't make one that can't tolerate a really small diameter difference, but "probably shouldn't" and what's actually out there are often different things aren't they?

And just because there are sensors out there than can measure it doesn't mean the manufacturer set up the systems to tell you about it before you burn up the coupler.

What did I say earlier? Buyer beware? If you don't know enough about your car to know this stuff then you don't know enough to make good decisions about things when someone tells you that you have to replace all 4 tires at the same time. Or if some sketchy cheap tire place says you don't and it'll be fine!
How do they account for tolerances in manufacturing? Can't tell me every tire is manufacturered to the EXACT same diameter. But I guess there is a sensor for rhat!!

Uh, yeah, if it's far enough out of tolerance there IS a sensor that will tell you that, probably several, as we've already covered. And that's why some manufacturers recommend sequentially made tires, as Rob has pointed out.

Why is this so hard to grasp for you? I'm sure you wouldn't tell someone to run two different size tires on the back of their A-body with a limited slip differential, so, if you consider that some of these AWD cars now had differentials front, rear and MIDDLE, between the front and rear, it would mean all 4 tires need to be the same size right? That follows directly from a differential between the front and rear.

And that's before we even talk about traction control, ABS, and all the other fancy sensor and ECU based stuff that happens on most modern cars, even on ones that aren't AWD.
At work I do 2 at a time all the time.
And I had a weird one on a car at work that I actually did put a set of 4 onto...
Even though I put a set of 4 on this car (think it was a Pontiac G6) we had a problem with it pulling. We sent it for an alignment. Still pulled.
Swapped tires around (remember a set of 4 put on together, all same brand and model and size/ at least as marked) we ended up sending it to another alignment place, this one actually had access to a frame rack for pulling bent frames after a wreck. They solves it.
Seems that 1 of the 4 new tires was 1/4" shorter than the other 3.
And on that note when my son first got his ramcharger we went to a wal Mart and we looked at what they had. I pulled 3 different brands of 31-10.50-15 off the rack and set them side by side. A Firestone a Uniroyal, and (at the time, I don't think they sell these anymore) a "liberator". All 3 were supposed 31/10.50-15 as marked All 3 were different outside diameters. So much for conformity...

Tires are frequently VERY different sizes from one manufacturer and tire model to another. Just because it says a certain size on the tire doesn't mean that's what it actually measures.

As for the 2 tires at a time thing, yeah, it's fine on some cars. And not at all on others. Hopefully your work knows the differences when it's making its recommendations.
 
I don't think we have any awd anything. And most of the time it's left to me to decide if any tires are changed, and how many. Most go along with what I say in that respect and I often get asked what we should do. My only restraint is stick with OEM stock size for car at hand and were currently contractually obligated to use Goodyear products.
 
Something with a transfer case ain't near as picky as something AWD with a viscous coupling.
Wachya talkin about? This is a viscous coupler (not mine).
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Its used in the NP 229 transfer case.
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I don't recall ever installing just two new tires on with the 'AWD' but sure have run on the spare, and sure have swapped fronts to rears to even out the wear.
 
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Now that aint really right. First of all I see at least one vehicle there with 4WD, although I can't be sure its full time. Second of all several cars there may or may not have limited slip differentials. Finally at least where I grew up, those cars all have snow tires on the rear if not all four. That wasn't optional after Thanksgiving 'cause you would get a ticket for driving in snow on summer tires. Studded snows if you were serious.

:poke:
Of course in the spirit intended I agree. :)

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So you are saying these sophisticated computer systems can tell of there is a few mm of wear in an inflated tire? Full tread delth vs 1/2? We aren't talking truck tires.

Traction control and ABS are speed sensors. They dont know if one tire is 25" and the other is 25.1" at some discrepancy it can sense a rotational difference, but thats not this thread is discussing.

Tire manufacturers now recommend 5 years vs 10 years? Crazy. They sell 2x as many tires now. Some how 20yr old land speed tires are still ok. Wierd. Oh and when MT made a cost effective race front runner, they now are owned by Good Year. Now they wont sell them to you if they know it is for Bonneville. You have to get the land speed tires at $700 each despite SCTA approval on the old ones. Follow the money

Seriously?!
 
It's not about a date stamp. It's about the physical diameter, which is a very legitimate point. It's the buyer's job to learn about what they are buying.

So...do they need to be perfectly matched like a pair of drag slicks?

a $350 oil change is not other worldly expensive in the grand scheme of things. especially with high end euro cars.

let's say he's got an A8 with a 4.0

that's 9L of full synth at $12 a quart plus a $25 filter so you're at like $150. throw in an air filter, a few o-rings, crush washers, some air box wax, disposal, tax, envro fee and presto there's $200 easy money. labor's easily that balance at $150/hr to bring it out to $350

That's not even that far off for an SRT car. A filter and 7 quarts 0W-40 synthetic alone is $100+ without the dealer markup.

How do they account for tolerances in manufacturing? Can't tell me every tire is manufacturered to the EXACT same diameter. But I guess there is a sensor for rhat!!

Of course, every wheel has a speed sensor.
 
The part I boldfaced, about the front runners.
Ah ok. I didnt open your quote. Yes, absolutely! Per calls I made to MT. So, either lie, or be very gray when talking to them
 
Bonneville? Certainly not, I'm, uhh...building a Pro Street drag car!
The mistake I made was the speed rating. Are they good for 250mph? What are they going on...um, well, so..
 
"My local track wants 250mph fronts on anything faster than 8.50s."

Hang up and reorder them from a different number?
Never got an answer other than "we are to forward you on to Good Year now that they own us"
 
As closely as possible, yes.

Definitely no AWD crap for me...

I'll note I worked with a guy who had 2 different brands on his Outback for the entire 8 years I worked with him. He had 140,000 on the car when he left the company and the transmission/AWD was original.
 
Definitely no AWD crap for me...

I'll note I worked with a guy who had 2 different brands on his Outback for the entire 8 years I worked with him. He had 140,000 on the car when he left the company and the transmission/AWD was original.
I don't disagree. I always recommend against them when someone asks my opinion of what new car to get.
 

I live in the land of AWD vehicles. I know some shops will only do 4 tires. I have only ever done 2 at a time if one gets ruined and they are fairly new but have always replaced all 4 once they are worn. I wouldn't worry so much about summer tires but with winter tires I believe its more important to have similar grip levels back and front.
 
My wife drives a 2018 Envision but I would have to do some reading as to what kind of coupler they use between the front and rear drives. If it's a fluid coupler with some slip, tires with slightly different diameters wouldn't be an issue. If it is a solid or mechanical coupler, They should be very close to the same diameter. We just turned 60,000 on the odometer with the original Hankook's and it's time for some new rubber. The fronts are worn 1/32 more than the rears. Nothing a grand $ won't handle.
 
At the tire place today, the tire sign said if one tire is bad to replace all four tires at once, because one uneven tire can throw off the computers. That really sounds like a racket, since there is no road on the planet that is absolutely even and flat. Even a pebble on the road would throw off the equal-ness of the tires, so the computers are always calculating for uneven-ness... So one grain of sand of tread difference from one tire to the other sounds like a scam to sell tires...

My not the smartest sister got a flat on her new Audi. So a few days later a 48' air conditioned enclosed trailer showed up from Audi and transported her car three hours away to the dealership to replace all four tires, and then three hours back to her house a few days later for $2000. It just doesn't makes sense..

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B.S.
 
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