Different tire size front and back?

kevnmurphy · #1 10-09-2009, 10:11 PM

By rear tires are toast. And my front have about 1/3 life left. I have Michelin Latitudes on their now but would like to switch to the Bridgestone Duelers. Is it ok or possible to have a different tire size on the front and the back. I don't really want to get 4 new tires. I am worried about the tire revolutions being different with the all wheel drive system the X has. Anyways, any help is much appreciated.
Thanks in advance.

X5NTahoe4u · #2 10-09-2009, 10:33 PM

19's? off a 4.4.i sport?

kevnmurphy · #3 10-09-2009, 10:53 PM

Sorry, 20" off a 4.6is.

kevnmurphy · #4 10-12-2009, 05:13 PM

Anyone have any more info on this please.
Thanks

X5girl · #5 10-12-2009, 05:37 PM

All X5's have different size tyres front and rear. Don't they?

primetime · #6 10-12-2009, 05:39 PM

Yeah you can have different size tires on..I had 285/40/20 on the back of mine and 275/40/20 in the front. Don't go different on the middle number if you can help it (or second number of course). I had no tire problems or uneven tread wear issues. All was fine. If you have to do this, definitely would go bigger on the back, not the front obviously.

X5girl · #7 10-12-2009, 05:53 PM

The middle number is the profile so as the tyre gets wider, you need to go down on the profile. I have 315 35 20 on the rear and 275 40 20 on the front and these have the similar rolling circumference.

J.Belknap · #8 10-12-2009, 05:55 PM

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
275/40-20 4.3in 14.3in 28.7in 90.0in 704 0.0%
315/35-20 4.3in 14.3in 28.7in 90.1in 703 0.1%

I'd worry about changing over to a different brand and not changing all four, as sizing varies slightly between models, and brands.

Interesting that, as your rears wear down faster than the fronts, they become closer to a perfect diameter match, front to rear.

You could run slightly lower pressure in your new tires. I'd do it with no regrets if replacing with the same brand and model.

X5girl · #9 10-12-2009, 06:07 PM

Quote:

Originally Posted by J.Belknap

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
275/40-20 4.3in 14.3in 28.7in 90.0in 704 0.0%
315/35-20 4.3in 14.3in 28.7in 90.1in 703 0.1%

I'd worry about changing over to a different brand and not changing all four, as sizing varies slightly between models, and brands.

Interesting that, as your rears wear down faster than the fronts, they become closer to a perfect diameter match, front to rear.

You could run slightly lower pressure in your new tires. I'd do it with no regrets if replacing with the same brand and model.

Am I good or what?

kevnmurphy · #10 10-12-2009, 06:16 PM

That is my only concern. Switching brands. I don't really want to do all 4 as my front Michelin's have about 1/3 if not more life left, as I will be switching to the Duelers. So I guess it isn't a good idea doing front Michelin's and rear Bridgestone's? What could happen? Can I mess with the transmission my doing so?
Thanks for the input, I really appreciate it.