[XAlp]

Hi
I need to replace both my front 19” Continental Run Flats.
Was considering a different brand - any risk in having different brand but matching pairs per axle?
Best Run Flats these days?
Cheers

[Sasquartch]

In theory as long as the tyres are all star marked and within a few mm of tread depth you should be OK
I'm fairly sure you shouldn't run a brand new set at the front and a worn set at the rear (or vice versa) as this risks stressing the transfer box

[Jeff123]

If the transfer box is stressed by that, then surely the car is not fit for purpose. Are we in danger of being paranoid about it?

Just a thought!

[E60525d]

Originally Posted by Jeff123

If the transfer box is stressed by that, then surely the car is not fit for purpose. Are we in danger of being paranoid about it?

Just a thought!

Agree. How much people have actually had transfer box issues?

[Mikesmith2939]

I have Bridgestone RFT star marked on the back( not sure which ones ) and Bridgestone driveguard RFT non star marked on the front.

I replaced the fronts as there was a 3mm difference between them and the rears.

The driveguard were recommended by the Bridgestone website and my local tyre fitters.

I have not had any problems to date, and I have the xDrive F30 320i.

[doncarlyon]

Shouldnt cause any issues IMO.

When the car is turning, all of the wheels will be rotating at different speeds, so a few mm difference in tyre tread depth shouldnt be an issue at all.

Only thing you may notice is less traction but depends how bad the other tyres are.

[teaston]

As long as the circumference is within 1% and they are the same type of tyre (directional or asymmetrical) then it should be fine.

[NISFAN]

Originally Posted by E60525d

Agree. How much people have actually had transfer box issues?

Actually quite a few. Not many 335d examples but plenty lower model versions with cranky xDrive.

[TiredGeek]

Originally Posted by NISFAN

Actually quite a few. Not many 335d examples but plenty lower model versions with cranky xDrive.

I wonder why that would be? Surely it's the same unit they throw in anything, I'd have thought the 335d would eat it more than the 320d

[xpro]

Theres a lot of talk about the transfer boxes failing. Reading online, most of the issue appear to be in the US? You dont hear much about 335d's having the same problem.

The only ever BMW I witnessed the transferbox failing was an 06 X3 2.0d Xdrive. The box sized up completely. And when you think about it, xdrive has been out for years, in all X vehicles, all similar design and pretty buletproof if you ask me.

[Dazza4492]

Hi, I just replaced two new run flat bridgestone tyres 275/40/R19 101Y on the rear. I still have michelin 245/45/R19s on the front. went for my first drive and the transfer box is not happy. feels like its going in and out of gear when accelerating. juddering is the only way i can explain it. I agree how crazy that a few ml makes a difference. now trying to find the same brand for the front only two left in the country!!!!!!!

[alan2808]

I've had non star marked non run flat staggered 20 inch on my X drive for years with no problems but they are the same make

[Alscoob]

Originally Posted by Dazza4492

Hi, I just replaced two new run flat bridgestone tyres 275/40/R19 101Y on the rear. I still have michelin 245/45/R19s on the front. went for my first drive and the transfer box is not happy. feels like its going in and out of gear when accelerating. juddering is the only way i can explain it. I agree how crazy that a few ml makes a difference. now trying to find the same brand for the front only two left in the country!!!!!!!

Blimey old thread revival...

^^ depends on the tread you have left on the front, if you have 7.5mm on the rear as new and less than 5mm on the front that's likely to cause an issue. Also if your new tyres are xx24 date stamped and the fronts are a lot older xx20 there may have been a change in tyre sizing spec over the years.

There was a chap on here who recently had a new set of PS5's all round in correct sizes but the fronts were massively smaller than the rears in diameter, that caused the same problem as you describe, he bought a different set and problem cured.

[Ofield_94]

Originally Posted by Alscoob

Blimey old thread revival...

^^ depends on the tread you have left on the front, if you have 7.5mm on the rear as new and less than 5mm on the front that's likely to cause an issue. Also if your new tyres are xx24 date stamped and the fronts are a lot older xx20 there may have been a change in tyre sizing spec over the years.

There was a chap on here who recently had a new set of PS5's all round in correct sizes but the fronts were massively smaller than the rears in diameter, that caused the same problem as you describe, he bought a different set and problem cured.

You'd like to think that if you buy a specific sized tyre, the size you buy is standardised across all manufacturers to prevent this issue.

[Pentland]

Originally Posted by Ofield_94

You'd like to think that if you buy a specific sized tyre, the size you buy is standardised across all manufacturers to prevent this issue.

Same goes for shoes I suppose.

[Alscoob]

Originally Posted by Ofield_94

You'd like to think that if you buy a specific sized tyre, the size you buy is standardised across all manufacturers to prevent this issue.

Not quite...

All tyres conform with ETRTO – The European Tyre and Rim Technical Information. and they have a rolling circumference tollerance of +1.5% to -2.5% in mm.

This came from Continental...

[Ofield_94]

Originally Posted by Alscoob

Not quite...

All tyres conform with ETRTO – The European Tyre and Rim Technical Information. and they have a rolling circumference tollerance of +1.5% to -2.5% in mm.

This came from Continental...

Attachment 3433266

This is interesting. I always said my PS5's don't look as wide as the PS4S 's I took off