640d GC and run flats?

[gareth h]

Guys, some advice please, I pick up a Gran Coupe next week which is on 20" rims and run flats, I changed to non run flats on my old 123d and the ride / handling were drastically improved, are modern run flats better or am I likely to see the same sort of improvements if I bin them?
Thanks
G

[gareth h]

Thanks guys, I thought that might be the case.

[gareth h]

I'd give it a go on non run flats, not a direct comparison but on my one series it made a huge difference, the roads around me are pretty poor and I changed from 18" rims to 17"s as well that also made a huge difference, my old e 46 m3 came on 19" rims, it was common knowledge that it handled better on 18" rims,I changed and it was much more stable on a bumby road and didn't tramline, I changed from 19"s to 18"s on my old Monaro as well and it had exactly the same effect.
My view is that 18" rims with good non run flat tyres are the optimum size, might be worth picking up a set, you can always flog the 19"s to cover your costs.

[gareth h]

I collect mine on Wednesday, it's on 20"s as well, think I'll drive it straight to the tyre shop!

[gareth h]

Picked mine up this morning (on 20" rims), the ride wasn't as poor as I thought it was going to be, but the steering is a bit lifeless, hopefully there will be a bit more feel and feedback from non RFTs.

[gareth h]

Was thinking michelin super sports, but noticed am M6 GC on the forecourt which was fitted with P zeros which I hadn't considered,assume that these are factory fit as the car had only done 9K miles (it was up for 51k, 20 months old and 9k miles which worked out at approx £5/mile depreciation, I was almost tempted!)

[gareth h]

Guys, back on subject! I had a chat with Birds who recommended sport contacts, I'm struggling to get rears in 275/30/20 but can get them (and at a good price) in 275/35/20 which increases circumference by about 4%, any views on whether this would be considered acceptable?
Thanks

[gareth h]

Guys, just a quick update, I fitted Michelin supersports a couple of weeks ago, as many people have said the difference is night and day, much better than I thought would have been achievable on 20" rims, am very pleased.