[HerkHealer]

I currently have the Eagle F1 runflats on my car, but hit a massive pothole and put a huge bubble in my front passenger tire and now have bad vibrations at 70mph. The wheel was checked and is good. What i'd like to do is put a set of new Michelin PS4's on the front and leave the Eagle F1's on rear. They have TONS of tread left on them.

Would use the same tire size 245/35/20.

Do you think there would be any issues doing this ?

[Superjackson]

No issues, you'll be completely fine.

[choppedliver]

As above. I have Potenza S007 on the rear and PS4s on the front after a pothole destroyed the front left tyre.

[OnlyGerman]

Fine as long as not mixing run flat and non run flat

[thetreksters]

Originally Posted by OnlyGerman

Fine as long as not mixing run flat and non run flat

Why is this important?

[OnlyGerman]

Originally Posted by thetreksters

Why is this important?

Mixing is a big issue. Car will likely drive like shit, and could cause drivetrain issues.

[thetreksters]

Originally Posted by OnlyGerman

Mixing is a big issue. Car will likely drive like shit, and could cause drivetrain issues.

What drivetrain issues?

[HerkHealer]

Originally Posted by OnlyGerman

Fine as long as not mixing run flat and non run flat

I will be leaving the Goodyear Eagle F1's on the rear ,as I stated in the original message. They have LOTS of tread left on them. I'm replacing the fronts because the front right tire has a big bubble from a pothole and vibrates the whole car at speed.

So again, I will be putting Michelin PS4S (Non Runlfats) on the front end and will have the Eagle F1 Runflats on the rear.

I think what you were trying to convey is that we dont want to mix a runflat and non runflat on either the fronts or rears together. Is that right ? I can see handling issues because the runflats are so hard vs the non runflats.

[choppedliver]

I have run flats on the back and normals on the front. I can’t tell the difference except the PS4S has a bit more front end bite. I’ve done 5000kms since.

[HerkHealer]

Originally Posted by choppedliver

I have run flats on the back and normals on the front. I can’t tell the difference except the PS4S has a bit more front end bite. I’ve done 5000kms since.

NICE ! Thanks for that info. Exactly what I expected to happen. I'm going to replace the rears as well, but they only have 10k miles on them and have tons of tread left.

I think what OnlyGerman was saying is never mix a Runflat with Non Runflat on the fronts or rears. Meaning putting a Left Side Runflat on fronts, and Non Runflat on the Right side. I could see that being a problem.

[HighlandPete]

Originally Posted by gladesteen

I think what OnlyGerman was saying is never mix a Runflat with Non Runflat on the fronts or rears. Meaning putting a Left Side Runflat on fronts, and Non Runflat on the Right side. I could see that being a problem.

It is not recommended to mix runflats and non runflats, even axle wise. Definitely not on the same axle.

One or the other, for the best handling balance. Bridgestone don't even recommend mixing some types of their own runflats.

Personally I wouldn't mix brands on my BMWs, due to different characteristics.

[HerkHealer]

Originally Posted by HighlandPete

It is not recommended to mix runflats and non runflats, even axle wise. Definitely not on the same axle.

One or the other, for the best handling balance. Bridgestone don't even recommend mixing some types of their own runflats.

Personally I wouldn't mix brands on my BMWs, due to different characteristics.

If i'm not changing the size/diameter of tire vs what is on their now, i dont understand what it could do. Maybe a little less traction for the runflats vs the Michelin PS4S tires. It's getting awful close to me putting the extra set of winter wheels / tires that came with the car, so this may be all a moot point. ChoppedLiver has been running the exact setup I planned on doing for several thousand miles though.

[choppedliver]

I guess my point of view is whilst not ideal, I’m not driving a race car and yes there may be some differences but there is a computer that handles traction issues whether due to road surface or tyre differences. The S007 and PS4S are both Ultra high performance tyres and the differences in wet and dry from tyrereviews is less than 1%. I don’t see any issue.

I would add that we don’t have tyre/wheel insurance in Australia or not that I’ve seen and I lost the front left due to a bubble at 1500kms from new so I wasn’t going to throw away all 4 tyres. It’s a waste (environmentally and otherwise) and money down the drain.

I could have put a new S007 on but due to covid there were none in country for 8 weeks so that was not an option.

Of course tyre manufactures and BMW won’t recommend it because it may change the handling/stopping/acceleration characteristics and is likely a blanket statement to stop people putting eco tyres on one axle and UHP on the other.