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my tire sizes are front for 225/45-17 and 245/40-17 for the back.

Can i just put the same size of the front on the back?

what would happen?

Its a BMW 330i 2001 rear wheel drive!

I would check with Tire.com and see what they have for your car....

the 225/45-17 are ...225 is (converting to inches) 8.86 inches, times 45%, equals 3.99 inches.. take that times 2 for top and bottom of tire, 7.98 and then add 17 inches for the wheel...you get. 24.97 inches tall wheel and tire...being 8.86 wide at the bulge.

the 245 is 9.65 inches, times 40% equals 3.86 inches, times 2 for top and bottom, 7.72..add the 17 to that and you get 24.72 inches high with a 9.65 wide bulge.

so the difference is pretty much the width at the bulge, being .79 or about 3/4 inch wider..with only 1/4 inch difference in height. Unless the wider tire would rub on the front fender, I see no problem...

But check with a tire shop, just to be sure.

If you put the same sizes on front and rear you will change the handling balance that BMW spent millions of Euro's honing to perfection and make the car more likely to crash.

I,

I am seeing a 01 330i has the original equipment size of 205/50-17... both front and rear, but only on the base package.

So you must be fortunate enough to have a Sport Package edition. Nice ride.

It was engineered to have 225/45-17, front, and 245/40-17, rear. Don't mess with that combo to save a few bucks. You have a very good automobile, treat it right and get the tire sizes that were intended. Otherwise, it will not handle and control the way you expect. Stay stock.

You can do that, but why?

You will not save much if any money putting matching tires all around. You will, however, affect the handling of the car. Not to a dangerous level but still.

The car is designed this way and they know much more about cars than we do, do what they recommend.