J28S

I need some education. Long story short...I have run flat tires. Front alignment is out (new car...6 months old) and the tires are wearing badly. I bought 4 new non-run flat tires (in garage ready to be mounted). Note: 225 front, 255 rear.

Question:
The rear OEM run flat tires are in great shape, but the front OEM run flat tires are shot. I was told that you can't mix run flat tires and non run flat tires (i.e. fronts not being run flats, rear being run flats). Why is this?

So let's summerize, new BMW (6 months old), needs tires and a new alignment. BMW's response...sorry not our problem. We don't warranty the tires and the alignment is under warranty for the first 2,000 miles. Not impressed, but that's life....could always be worse.

Honda318dx

Should have bought the TL

drkarrow

Look up "Lemon-Law" in your state. That's realy messed up. There's no real reason you shouldn't be able to mix the tires. But whenever you change the tires on one end of your car and not the other, you can greatly change the handling characteristics.

o-man

Are they the "same" tire, or two different brands? The biggest difference you will feel is impact harshness. The non-run flats wont have as stiff a sidewall and should weigh considerably less. Try it, if it feels weird, install the other two tires

J28S

Corey - Yep, your right...I should have got th Porsche Cayman instead.

I can understand that the RFT has a firmer sidewall than a non-RFT. But didn't know companies couldn't sell you two tires if you still had RFT on the rear. Also, just trying to understand exactly(technically) how N-RFT and RFT mixing would drastically upset the handling.

Yes, if I put just the front tires on...I would have two different brands of tires on the car.

Lemon Law in this state wouldn't help with tires and an alignment. BMW could argue that I hit something which caused the car to go out of alignment.

Guess I'll be TESTING the OEM tires tonight to see how long it takes for the tires to gain traction when reving up the motor and dumping the clutch (didn't say burnout). I'll also test the LSD out and see how well it works in different situations excellerating from a stop. Hey, I'm gonna get every cent / ounce of fun out of those tires before I get the new tires mounted and an alignment.

O-man - I may go ahead and do it for a day just to see first hand how harsh the difference is.

Thanks again.

My95SlvrBlt

It could have been much worse. Picture yourself in a touareg... Theyre the same, if not worse for tire problems.

J28S

Well, here's the update. Got the front two on the car and drove the **** out of the car...couldn't tell a difference (that is the car had a problem with non-RFT in front and RFT in the back). Next day, I got the rear tires put on. I will say that the OEM tires performance wise are pretty sweet (that is DAMN good).

Question #2: Why is it that BMW uses sand bags for an alignment? Would it benefit other cars (i.e. Acura Integra) to have this done the same way? Just curious.

xerox445

Sitting in the car changes the alignment of the car slightly, weighting it compensates for the driver weight and keeps the car a bit better aligned.