[max_k20]

I'm in need of 2 rear tires and looking on tire rack I see the Continental ExtremeContact DW in 255/35/zr18 on sale on tire rack. Would it be possible to run these in the back with almost brand new oem re050 in the front ? I heard some people say its ok and other say its not. Could also someone confirm this is a RFT tire ?

Also anyone have review of these vs re050a as they are better rated on Tire rack.

Any help appreciated.

[zipstic]

I’d be leery of running different tire models front and back. Theoretically if you can find tires that have the same revs per mile you could get by without any harm to the xDrive system. The tires will perform differently too fwiw.

The Contis are not run flat. They make the RE050 in both a run flat and non-run flat so you’d have to look more closely at the tire.

[335xi Kevo]

Originally Posted by zipstic

I’d be leery of running different tire models front and back. Theoretically if you can find tires that have the same revs per mile you could get by without any harm to the xDrive system. The tires will perform differently too fwiw.

The Contis are not run flat. They make the RE050 in both a run flat and non-run flat so you’d have to look more closely at the tire.

Agreed. You can run whatever tires you want, all 4 being different even as long as the revs were the same.

I personally would run 2 different sets, each tire has a different characteristic.

Also with all AWD cars. You cant just replace one or 2 tires without the potential to be out of the RPM range and burn that poor transfer case up.

[max_k20]

In same as oem size rear re050a are 830 rev per mile and continental are 828 rev per mile. Is that ok or must be exact same rev per mile ?

But i think ill just buy another set of re050a

[zipstic]

You would be ok in terms of revs per mile being close enough. People say 1% is the max difference, but I a lot of people recommend 3-5 RPM max difference.

[max_k20]

Even tho price was better on conti went with another set in the back of re050. Front one only have 8000km on them and will wear less faster than front.

[Temonio]

Aside from what others have mentioned, you also run a risk in inclement weather with different tread patterns.

[BMW_Belgier]

THIS IS SAFETY RELEVANT!

I strongly recommend you, not mounting 2 different kind (brand, model) of tires! This is not safe!

In my country it is even forbidden and, when caught, they will forbid you to drive your car!

[Temonio]

Originally Posted by BMW_Belgier

THIS IS SAFETY RELEVANT!

I strongly recommend you, not mounting 2 different kind (brand, model) of tires! This is not safe!

In my country it is even forbidden and, when caught, they will forbid you to drive your car!

That's what I was getting at. When I used to sell tires, we learned what happens when you do this. The way they react in the rain can be pretty dangerous.

[Timmayy]

First off, there is a Tire & Wheel specific sub-forum, which is where this belongs. One of the mods there works for Tire Rack and he is very active in the forum.

It is a very bad idea to mix and match tire brands or models as the construction of the tires can vary significantly by tire model, even from the same manufacturer. This can lead to unsafe handling, especially in emergency situations.

For example, I had a 1990 300ZX I bought used, and it had one odd tire on the left rear. It was the same size as the others, but the shape of the tire was significantly different. I planned to replace them all but wasn't in a hurry to do so. That is, until one morning on my way to work I was taking this fairly sharp on-ramp at a good rate of speed and that left rear tire let go, at which point I spun 360 onto the highway. Fortunately there was no traffic passing by at that moment, or it would have been very bad. Needless to say, I got new tires for it within the week.

It's not that big of a deal to mix tires on that beater Civic with different colored doors you see on your way to work, but I would never do it on a car that I actually valued.

[arlingtonassasin]

I asked a BMW whiz this same question and he mentioned it would be fine as long as the rolling circumference was the same. This chart of my staggered set-up shows how extremely close the tires are. well within the 1% range that seems to be the standard thinking:

[catcher22]

replace all 4 tires

I'm sure many of us have considered replacing one or two tires at some point.

Especially with AWD, just replace all 4 or at least get the same tire/type