OK to mix run flat with regular?

Hey everyone,

I have a 2011 mustang running 2 wider tires in the back. (275/35/19s with 5000 miles on them or so. The back passenger one developed a bubble so today I had to get it replaced last minute. (Needed it done today) tried several tire shops near me and the only one that had the correct size had a run flat tire. (Almost Brand new with the same mileage and tread left as my current tires)

My question is, is it ok to drive with 1 regular tire and one run flat in the back as long as they’re the same size and tread?

I’ve called several mechanics and the general consensus was yes, however I’ve read on the internet to not mix brands/types even if they’re the same size and tread so i’m not sure what’s correct…obviously whenever possible you should run the same 2 tires on each axle but would there be any major safety or handling issues that could come up by doing this?

No. The handling characteristics are too different. Yes this is a safety issue, ESPECIALLY on a solid axle Mustang.

I would not recommend different models of normal tires side to side let alone a run-flat and a standard tire on the same axle.

Plus they are trying to destroy your traction-loc differential as you drive.

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If changing from run-flat to conventional tires, replacing all four tires is highly recommended. Mixing run-flat and conventional tires can significantly reduce the stability of vehicle handling.


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Another vote for not having those different tires . Also what kind of a tire shop would even do that?

Kind of unrelated but whats the widest rear tire i could safely run on a 2011 stang?

Besides safety you also want to consider damage to underbody of vehicle if they stick out too much. You’ll also see a degradation in performance and fuel economy with wider tires.

The tire rack web site will show what tire and wheel combinations can actually be used on your vehicle . Since they are almost the gold standard for such things that is where you should look . But if you really want your Mustang to handle as it should I think maybe Ford knew what they were doing when they built the car. You do realize that putting too wide of tires on stock rims might not be such a good idea.

It is not safe at all. the geometry of the car will be ruined…

With the correct wheel offset a 305 wide tire will fit inside the fenders… 305/35/18 or a 305/30/19 on an 11 inch wide wheel with 50-55 mm offset should fit easily.

Wider is possible but the flange in the wheelhouse may need to be removed and/or the fender lips may need to be rolled.

You likely need an adjustable panhard bar (track bar) to center the axle if the car has been lowered.

You can fit a 295 front tire on as well but the wheel offset needs to be about 40mm or a 12mm spacer needs to be added with longer wheel studs. A 305 can be squeezed on the front in some instances.

Edit: CJ Pony Parts offers several wheel and tire package with 19x9.5 inch front wheels with 275/40/19 tires and 19x11 rear wheels with 305/35/19 tires.

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