# Replacing tires on one side of car **URL:** \ **Category:** Factual Questions\ **Created:** [October 13, 2015, 1:15am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504 "2015-10-13T01:15:10Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![iceiso](https://avatars.discourse-cdn.com/v4/letter/i/3be4f8/32.png) [@iceiso](https://boards.straightdope.com/u/iceiso)\ **Post date:** [October 13, 2015, 1:15am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/1 "2015-10-13T01:15:10Z")
Hello, I had an unfortunate collision with construction material that fell off the back of a truck. I ran over what appeared to be a 4x4 square tube. Both tires on the drivers side were destroyed. The current condition is new tires on the drivers’ side, old tires on the passengers’ side. Some details: - My wheels are staggered; the rear tires are wider than the fronts, and therefore cannot be swapped front–\>rear and vice versa. - My tires are not directional; passenger/driver front can be swapped. Same for the rears. - The tires are relatively expensive, ~$225/each - Tread depth of passenger (old) side are at 66%, or 7/32" depth - Tread depth of drivers (new) side are 100%, or 9/32" depth The reasoning for not replacing all 4 tires is that if I do so now, I will be throwing away (2)x66% tires. Instead, I will replace them all when the passengers’ side reaches 0%, at which point the drivers’ side will be at 33%. That way, I will be throwing away (2)x33% tires. My questions are: - What sacrifices am I making/risks am I taking by following this reasoning? - Are there any ways (short of replacing all 4 tires) to reducing the risks? ie. placing the new tires at opposite diagonal ends of the car. - What would you do? While my hope is that someone can validate my decision to not spend more money, I am not opposed to biting the bullet and replacing the old tires as well, if it presents a safety issue. Thanks for the input! ---
**Author:** ![Absolute](https://avatars.discourse-cdn.com/v4/letter/a/b2d939/32.png) [@Absolute](https://boards.straightdope.com/u/Absolute)\ **Post date:** [October 13, 2015, 1:26am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/2 "2015-10-13T01:26:19Z")
What kind of car is it? Most likely, the manufacturer has a specification for the maximum allowable variation in tire diameter on the same axle. Even if you do not have a limited-slip differential, most modern cars have traction control systems that will throw an error and disable themselves if the difference in diameter is too great. The easiest option is to call or visit the dealer, and find someone knowledgeable to ask what the maximum is. You want an actual, quantitative specification from the maintenance manual, not just a verbal assurance that it will be fine from a service advisor. You can also check the manual. If you have a performance car with a limited slip differential, or something like an Audi with a fancy AWD system, you can physically damage it if the difference is too large. If your car is running expensive, staggered tires, this might be the case. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [October 13, 2015, 3:00am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/3 "2015-10-13T03:00:06Z")
> [@iceiso](#): > > - What would you do? I’d replace all 4 tires, which is pretty much required on my AWD vehicle. I had to buy 4 new tires after trashing just one. I suspect you are risking differential damage and poor, possibly dangerous handling on turns. It depends on what car you have. ---
**Author:** ![iceiso](https://avatars.discourse-cdn.com/v4/letter/i/3be4f8/32.png) [@iceiso](https://boards.straightdope.com/u/iceiso)\ **Post date:** [October 13, 2015, 3:47am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/4 "2015-10-13T03:47:30Z")
> [@Absolute](#): > > What kind of car is it? > > Most likely, the manufacturer has a specification for the maximum allowable variation in tire diameter on the same axle. Even if you do not have a limited-slip differential, most modern cars have traction control systems that will throw an error and disable themselves if the difference in diameter is too great. The easiest option is to call or visit the dealer, and find someone knowledgeable to ask what the maximum is. You want an actual, quantitative specification from the maintenance manual, not just a verbal assurance that it will be fine from a service advisor. > > You can also check the manual. If you have a performance car with a limited slip differential, or something like an Audi with a fancy AWD system, you can physically damage it if the difference is too large. If your car is running expensive, staggered tires, this might be the case. It is a G37 sport. I’ve driven about 20 miles with the aforementioned difference and haven’t gotten an error yet. I’ll check with a dealership tomorrow for acceptable specifications. IF I’m outside of the spec, I wonder if insurance will cover replacement of two more tires… I have some homework to do! ---
**Author:** ![iceiso](https://avatars.discourse-cdn.com/v4/letter/i/3be4f8/32.png) [@iceiso](https://boards.straightdope.com/u/iceiso)\ **Post date:** [October 13, 2015, 3:54am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/5 "2015-10-13T03:54:39Z")
> [@Telemark](#): > > I’d replace all 4 tires, which is pretty much required on my AWD vehicle. I had to buy 4 new tires after trashing just one. > > I suspect you are risking differential damage and poor, possibly dangerous handling on turns. It depends on what car you have. I’m leaning that way now as well. As I wrote my original post, I started to figure: 1. If I replace my tires now, I’m throwing away (2) x tires with 66% life. 2. If I replace them later, I’m throwing away (2) x tires with 33% life. Option 1 will result in (2)x33% more “waste”, valued at about $150 (.66 x $225). $150 to ensure even handling and wear on the drivetrain, for the next several years, is probably a good investment. ---
**Author:** ![snowthx](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowthx/32/10660_2.png) [@snowthx](https://boards.straightdope.com/u/snowthx)\ **Post date:** [October 13, 2015, 4:21am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/6 "2015-10-13T04:21:51Z")
I got a big staple in the sidewall of the rear passenger side. Tire shop offered to replace them all (still had about 2/3 tread left), or just the rear two. I did just the rear two, and they credited me for mileage left on the two replaced. Spent about $150. Granted, mine were same axle, but maybe you can get credit for tread left on the damaged tires? ---
**Author:** ![Absolute](https://avatars.discourse-cdn.com/v4/letter/a/b2d939/32.png) [@Absolute](https://boards.straightdope.com/u/Absolute)\ **Post date:** [October 13, 2015, 5:22am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/7 "2015-10-13T05:22:02Z")
Some years of the G37 sport came with a viscous limited slip differential. Theoretically, a differentce in tire size on the rear axle could cause the differential to overheat and the limited slip functionality may be damaged. I don’t know how much of a difference is required but you should definitely find out. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [October 13, 2015, 5:31am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/8 "2015-10-13T05:31:19Z")
You could also just replace the tire on the driven axle. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [October 13, 2015, 6:51am UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/9 "2015-10-13T06:51:05Z")
For the benefit of anyone who might otherwise have to Google it (as I did), a G37 is a model put out by Infiniti. ---
**Author:** ![herman\_and\_bill](https://avatars.discourse-cdn.com/v4/letter/h/f1d935/32.png) [@herman\_and\_bill](https://boards.straightdope.com/u/herman_and_bill)\ **Post date:** [October 13, 2015, 2:48pm UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/10 "2015-10-13T14:48:45Z")
Buy 4 tires. As they wear, start rotating in the used tires. Meanwhile, put the 2 used tires up for sale at a reasonable price so you don’t have to bother with them. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [October 13, 2015, 2:52pm UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/11 "2015-10-13T14:52:55Z")
Slightly off-topic: are you sure the wheels themselves weren’t damaged? ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [October 13, 2015, 2:53pm UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/12 "2015-10-13T14:53:53Z")
I’ve heard that it’s possible to buy only one tire and have it ground down to match the others. You’d be throwing away 33% of the tread life on the new tire, but it might be a better option than throwing away 66% of the tread life on 2 tires. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [October 13, 2015, 3:03pm UTC](https://boards.straightdope.com/t/replacing-tires-on-one-side-of-car/734504/13 "2015-10-13T15:03:01Z")
[Tire Rack](http://blog.tirerack.com/blog/motorsport-messages-from-marshall/tire-shaving-available-at-tire-rack-v2) will shave down a replacement tire like that. Too late for the OP, but I imagine brick-and-mortar installers offer a similar service.