Hello,

To make a long story short I'll spare the details. Here's my question.

I need to get my Mini to the tire shop 9.5 miles away on a very curvy canyon road - is it okay to drive the car w/ 1 tire slightly bigger than the other 3?

Detail of the mismatched tires: the front-right tire has a temporary 225/40/18 (non-run flat) while the other 3 tires have 205/40/18 run flats.

The vehicle has been sitting in the driveway, hasn't moved an inch, but I'm swapping all 4 of them out for a better set of non run flats next week.

Would it be safe for the drive train if I just lowered the PSI on the 225/40 a bit to match the hight to the 205/40 on the other side of the axle and drove it down the canyon 9.5 miles to the tire shop?

Thanks for the help and suggestions.

 

225/40-18 has a tire diameter of 25.1" which is normally too tall for the MINI and likely could rub in the rear. Not sure about rubbing in the front but with a stock rim it might be OK.

Yes you can drive 10 miles but keep tire pressures up about 36psi in each tire. When you deflate a tire you loose handling capability and load capability.

My other idea is to put the mismatched tire on the rear but I think it could rub worse.

Drive slow like the speed limit and see how the handling is for the first few miles. You can always drive with the emergency blinkers on and at about 5 mph slower than the speed limit. You could act like you had a temporary spare tire on- which should always be on the rear not front even if you flat a tire in the front.

It is possible that your flat tire light will come on due to the different sizes of tires. You can reset it.

 

Yep...put the mis-match on the rear and you'll be ok.

 

Would it not be better to have the rear rub than have the differential spin at different speeds on each side? Would that be what would happen?

 

If you have mismatched tires always put them on the non drive axle.

 

I agree with everyone in that the mismatch should be on the non drive axle. This is especially true if you have a limited slip diff.

 

If you put the mismatched tire on the rear and you drive slow or at speed limit and smoothly then even with a little less than perfect handling you will be OK. Don't load up the rear if you can. The spare tire is already 225mm wide which is more than stock.

However if you drive fast in corners you may find that the staggered tire on the back can alter normal handling and allow for greater tendency to turn in one direction or to be more or less loose (less traction) in the rear.

 

when you use a donut spare you are driving on unmatched wheels right? Yes I realize we're talking smaller vs larger....but the size dif' is significant

No perm' harm in the short term....even on the drive wheels..... I mean, who swaps wheels around so the spare is only on the non-driven axle?

 

that's what I was going to say: "Yep...put the mis-match on the rear and you'll be ok."

 

Swapping the compact spare so that it fits on the rear axle in case of a flat on the front IS recommended and the best thing to do whenever you can.

Handling with one compact spare in the front for a MINI would be less than predictable or safe. If you were stuck in the middle of the night on a busy or isolated road and just needed to get going you can drive on the spare but go slow and be careful.

If you see another car driving on a spare with it on the drive axle then be cautious and steer clear.

 

Appreciate all the suggestions. I swapped the larger tire to the back just for safe measure and will drive the car to the shop tomorrow.

Say goodbye to the POS run flats!