New owner

Just replace your run-flats with Goodyear Eagle F1 A6's and stick with the original sizes, increasing the profile will increase the diameter of the rear tyre, from 631 mm to 657 mm, so an increase of 26.0 mm, this will reduce the amount of torque at the rear wheel by 4%! The 255 rears are also louder than the 225 fronts, and so you could go with a 225 square set up, purchasing another set of fronts and fitting them to the rear.
 
I went up one profile on the rear tyres on my E86M from 255/40 to 255/45 and didn't notice any lack of torque, although I didn't notice any improvement in ride quality either!

The only downside with fitting fronts on the rear is they will look a bit lost in the arches unless you add a spacer.
 
The only time an increase in rolling radius will manifest in torque related matters is only at max speed..then it’s BHP not torque for that issue..

As long as the area under the torque curve remains the same the reality is that changing gearing by say 5% has no perceived impact ..unless..for example it changes the shift point for a 0-60 or 0-62 dash..

I wish I’d changed my profiles years ago…
 
Also worth noting that changing the rolling radius of the wheels, ie increasing profile percentage, can confuse the 'puters and make the DSC unreliable.
 
Pondrew said:
Also worth noting that changing the rolling radius of the wheels, ie increasing profile percentage, can confuse the 'puters and make the DSC unreliable.
Click to expand...
That only applies if the front / rear rolling circumferences are mismatched by more than say 1%-2%…and that’s on the E85/E89…later Z4s could cope with major differences….FWIW
 
Hi all and happy new year!

As you may remember, I'm looking at removing my run flat tyres, anyone else tried this and what tyre make did you choose please?

Thanks
 
It all depends on what you want to spend. If you go for a premium tyre Mitchelin PS4s & PS5s always get rated well as do Continental SP6 & SP7.

If you went for a mid range tyre Khumo tyres get rated well.
 
I fitted a set of Kumho Ecsta tyres to my car in 2022 and they were fine. I had to fit new rear tyres earlier this year but left it too late to get Kumho again so I bought Hankook Ventus and if anything they seem to grip a bit better than the Kumhos did.

sars suggested Goodyear Eagle F1 which also seem pretty popular on here but there are plenty of other options. It might be worth looking at online tyre reviews too.

I'd avoid Michelin Pilot Super Sport though. My car came on those and while they were great on a warm dry day they were hopeless on a chilly damp day, which is far more common in the UK sadly.
 
Thanks all for the tyre advice, here's some pictures for you
 

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Hi All!
I hope you're all well
I'm having some problems with my Z4 power steering, it all started (i think) when I took the wheels off, since then warning lights and power steering only working now and then!
Anyone had anything similar?
Thanks
 
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