In the tire plugging thread an issue came up about having to replace all four tires if an issue came up with one tire and it had to be replaced. I've heard that before, and if it's true, why does the vehicle even come with a spare tire if the computer will shut the vehicle down?
Regarding the tire plug thread....
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In extreme weather environments it is important to replace all four. Driving on snow or ice coated roads or continually wet road from rain, cornering and braking won't be equal with different tread patterns or wear.
It's about as foolish as saying both calipers have to be replaced if one gets stuck. It's a sales technique. I've had mechanics tell me "It's the law." Ask them to show you the "law." They won't find it.
I don't know about the computer shutting it down... Really? If have an 2022 AWD car with a spare, and I assume if I were to get a flat and change to the spare I could limp along somewhere to get the punctured tire fixed.
I've been told the same 'one-means-four' thing, but always counter with what I was told way back when. To wit, a good argument can be made to closely match the condition and wear of both tires on the same axle, i.e., front or rear to avoid handling problems. Normally, the best pair of tires should be on the front. By the same token, most cars have some type of electronic stability control, so one would think that would compensate for some of these theoretical handling problems, rather than shutting the car down.
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^^ What Eric said. It depends on the state of the tread wear. On a front wheel drive car, you wouldn't want a brand new tire and a 50-70% worn tire on the drive axle.
I've been in this situation recently. I bought the new tire and put it in the back. No problem. When the other three tires finished wearing, a bought a set of four and used the "new" tire for the spare.
I've been in this situation recently. I bought the new tire and put it in the back. No problem. When the other three tires finished wearing, a bought a set of four and used the "new" tire for the spare.
I mentioned in the other thread that, from my reading, shaving the new tire to match the three remaining older tires in tread depth is a cost effective approach.
LVSteve
Member
The computer won't shut the car down, but it may well complain if the wear difference is too great.
One 'fix' has been to all but eliminate the spare wheel as a thing in a modern car.
ACORN
Member
Funny. We bought an AWD Astro Van used from a GM dealer with about 12K on the odometer. There wasn’t 2 tires the same on it.
How do you shave a tire ?
Same principal as a lathe.
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Gillette; the best a tire can get.
Don't forget the Foamy!
I would consider that to be potentially dangerous. 4 different tires with different handling characteristics.
I ran into this at a dealer in Greenville, SC when looking for a car for the Crypt Keeper. Dealer told me if I wanted 4 matching tires, to go buy them. I did not buy the car but it was fun writing the Google review.
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ACORN
Member
I would consider that to be potentially dangerous. $ different tires with different handling characteristics.
I ran into this at a dealer in Greenville, SC when looking for a car for the Crypt Keeper. Dealer told me if I wanted 4 matching tires, to go buy them. I did not buy the car but it was fun writing the Google review.
I’m assuming someone at the dealer or wherever need the tires. Put together a set of 4 that kinda matched from the used tire pile, and swapped ‘em.
I didn’t notice it when we bought it.
Those 4.3L engines are strong!
I wish GM still made the Astro.
Jeff423
US Veteran
FWIW: I once drove a 2019 Subaru (rental) from Eugene to the Portland airport on the tiny spare. Apart from having to stay at 55 I had no problems and didn't hear or see anything from the computer.
I generally replace my tire in pairs. 2 new go on the front and then ones from front being replaced move to the rear, bu I run rear wheel drive cars. But front or rear wheel drive the best tires belong on the front.
There may be some difference on "all wheel" drive cars, but few of them are actually all wheel drive. With the vast majority the transfer case and differential are NOT limited slip/ They accomplish all wheel drive by reading the wheel speed and dragging the brake on the slipping wheel IF it is slipping X amount more than the others. There needs to be a certain amount of leeway in the compute that controls this, or a low tire, uneven wear, un even loading would cause problems.
IF your tire's diameters are close the computer doesn't care about tread pattern
If it was really precise a low tire would cause it to drag a brake, causing a hot brake and excess brake wear as well as diminished ability braking on that wheel when it was hot
There may be some difference on "all wheel" drive cars, but few of them are actually all wheel drive. With the vast majority the transfer case and differential are NOT limited slip/ They accomplish all wheel drive by reading the wheel speed and dragging the brake on the slipping wheel IF it is slipping X amount more than the others. There needs to be a certain amount of leeway in the compute that controls this, or a low tire, uneven wear, un even loading would cause problems.
IF your tire's diameters are close the computer doesn't care about tread pattern
If it was really precise a low tire would cause it to drag a brake, causing a hot brake and excess brake wear as well as diminished ability braking on that wheel when it was hot
Having all wheel drive cars, that came with those temporary spares, I not only read the owner's manual, I checked with brand certified mechanics.
If you have to use the temporary spare ON ANY VEHICLE, you need to put it on the rear axle. You want the front tires to be (pretty much) the same for steering control and stability. The rear differential will take care of any slight differences in rolling radius.
What the Subaru manual noted was that the OD/rolling radius of the temporary spare is designed to keep any difference in tire RPMs within the limits of the software.
Despite that, if I was planning a long trip somewhere with wide open spaces, I think I'd find room for a full size spare with some wear on it. Maybe match the OD of the temporary spare.
If you have to use the temporary spare ON ANY VEHICLE, you need to put it on the rear axle. You want the front tires to be (pretty much) the same for steering control and stability. The rear differential will take care of any slight differences in rolling radius.
What the Subaru manual noted was that the OD/rolling radius of the temporary spare is designed to keep any difference in tire RPMs within the limits of the software.
Despite that, if I was planning a long trip somewhere with wide open spaces, I think I'd find room for a full size spare with some wear on it. Maybe match the OD of the temporary spare.
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One would think new tires should go on the front, right? Maybe that thinking is just as factual as being out in the cooler weather will give you a cold.
https://www.allstate.com/resources/car-insurance/new-tires-front-back
https://www.tirebuyer.com/education/new-tires-front-or-back
https://www.tirerack.com/upgrade-garage/does-it-matter-which-position-my-new-tires-are-mounted
Where to Replace and Install Two New Tires | Goodyear Tires
6 Common Tire Myths Debunked
I'm not advocating either point of view, as I usually replace all four tires when a replacement is needed.
https://www.allstate.com/resources/car-insurance/new-tires-front-back
https://www.tirebuyer.com/education/new-tires-front-or-back
https://www.tirerack.com/upgrade-garage/does-it-matter-which-position-my-new-tires-are-mounted
Where to Replace and Install Two New Tires | Goodyear Tires
6 Common Tire Myths Debunked
I'm not advocating either point of view, as I usually replace all four tires when a replacement is needed.
I hardly ever rotate my tires, I know its better to do so but around here you might sit for a half hour or it might be 2 hours depending on how busy the place is to do 15 minutes of work. I don't want to wait, so my tires don't last as long but I still get 55 to 65K miles out of set. I always replace all four at the same time even if one is newer tire that had to be replaced, I've never had a problem with the computer or sensor with a different tire, I just like 4 matching tires. I DO shop around on line and get a great deal when I buy tires and never pay over $500-550 for a set of All Terrain pick up tires. My last set was Goodyear Wrangler AT tires and they were under 500 bucks, I just enter my tire size on Google and see who's running the best sale.
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