I was about to install my winter tires when I noticed that one of them has developed two small bubbles in the sidewall since I stored them in spring.

I would just replace it with an identical unit but, unfortunately, it's a discontinued model (Michelin Pilot Aplin PA3) and I cannot find a proper replacement anywhere... which sucks, because they all have excellent tread life remaining.

I'd like to avoid replacing them with a brand new set, due to the expense. The newest iteration (PA4) isn't made in the same size that I have (235/45r18).

Since it's on a RWD car with factory staggered setup, I've considered replacing just the fronts with 225/45r18's or the rears with 245/45r18's in the PA4. Alternatively, there are other brands available in the 235/45r18 size that I already have.

I know TireRack et al claim never to run different tires together (or even different wear levels) because of safety concerns. How much of that is company CYA and salesmanship and how much actual safety concern is there for an attentive driver?

  • Are the tires still under warranty?
    – dlu
    Commented Nov 22, 2016 at 4:21

2 Answers 2


If your yearly vehicle inspection rules/laws allows it, then you dont have to worry about it as long as the tire sizes on the same axle are same. You can simply change a single tire. If having one different(but same size) tire was a "real" safety problem, they would have made a restriction about it in law.

Also ABS/ESC will balance the load in case one tire has less friction for any reason and slips. Even same brand/model tires can have slightly different frictions when you are driving anyway.

Of course the tire manufacturers and shops would tell you to change both tires on the same axle. Simply because of profits and it is easy to fool people when people rely on so called 'common sense'.

Below are links to few threads which also address the issue:

  • 1
    There are no periodic inspections required here for passenger cars; only when buying or selling. According to the official inspection guide, the only failure criteria for tires are differing sizes on the same axle or different ply types on the same vehicle, neither of which I'd do anyway. Commented Oct 22, 2016 at 22:16
  • It depends on where you live. Since I don't know where the poster lives. I did not want to assume anything. He should figure it out himself. Commented Oct 26, 2016 at 10:57

If you can find a single new one somewhere, take it to a Race Shop and have it shaved down to the wear level of the rest.

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