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

[smashy]

For my part ,changed my runflats 3 weeks in on my new F30 330d it felt as though I finally had rubber between me and the road ,plus the howling on many motorways and A roads was just silly,that has gone as well (18s).

Interestingly I had no issues on my previous car a 120d on 16s, seems size of tyres is a big factor

[cerb4.5lee]

I swapped the 20" run flats on our 640d(coupe) and it made a vast difference and I was well chuffed with the difference, the car was originally on Dunlop Sport Maxx GT run flats.

It even added a little more steering feel which the 6 series is renowned for having hardly any, it crashed and banged massively on the run flats and now its on normal tyres its only the odd occasion now because the rims are still a decent size to be fair.

Best decision we made and my mrs agreed too.

[cerb4.5lee]

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

A bit more discussion.

[andrewr]

I changed my 640 GC from Dunlop run flats to Continental sport contact 5 in the standard size at standard pressures, massively better.

[gareth h]

Thanks guys, I thought that might be the case.

[turboman786]

Wow, I was just about to start a thread on this topic!
Had my 640dgc for 3 weeks and beginning ti think I've made a huge mistake.....have owned 16 bmws in my lifetime and all have driven well....until now...it's on 19s with rfts and has adaptive suspension but it's just terrible on the road.....crashy, skips about, feels strangely disconnected. ...just terrible for an otherwise stunning car

I'm tempted to either sell the car and go back to a 535d which rode beautifully on big wheels (ironically with rfts ) or go for non rfts.....bit I'd rather just sell the car than mess about changing tyres etc and find the problem to be still evident....

So so disappointed as the car is prestine and has so much optional kit that I thought I'd landed my dream car ......super high spec so I'm loathe to sell but will happily sell rather than put up with the awful ride

[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.

[moffat]

I've also ditched my runflats on my 1 year old 640d Coupe.

I've gone for Bridgestone S001's and couldn't be happier, it's made a huge positive difference.

No skipping round corners on poor road surfaces, vastly improved cold grip and overall bumps are less noticeable even on the 20"s. It's greatly improved the driving experience.

I managed to get a great deal through tyreleader for all 4 tyres fitted for £730 too and bought a Slime tyre kit from Amazon to see me through any puncture issues (that are not complete blow-outs).

I will never have RFT's on a car again.

[gareth h]

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

[rlg43p]

I'm taking delivery of a 640d SE Coupe on Friday and have had its standard 18" rims fitted with non runflat winter tyres. I'm hoping for a serene ride!!

[K&L]

moffat said:

I managed to get a great deal through tyreleader

Just checked by vehicle type on tyreleader and it recommends 265/35 R20 for the front as opposed to other websites (and the tyres BMW supplied) being 245/35 R20. Rears are the same at 295/30 R20.

Can't be right can it?

[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!)

[moffat]

[quote=K&L]

Just checked by vehicle type on tyreleader and it recommends 265/35 R20 for the front as opposed to other websites (and the tyres BMW supplied) being 245/35 R20. Rears are the same at 295/30 R20.

Can't be right can it?
[/quote]

I did it all manually:

245/35/20 on the fronts
275/30/20 on the rears

[moffat]

gareth h said:

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.

I doubt they will cure the steering that much, but the ride is better.

You won't notice it initially but hit a few bumps, cats eyes, and longer term you will notice the tramlining and other issues.

[anonymous-user]

I have RFTs on 20" on my 640d GC, and have driven a similar car with non-RFTs and it was immeasurably better.

Another major issue with RFTs, particularly on the 20s is that they don't react very well at all to hitting pot-holes, and the side walls tend to fold and bulge rather than bounce back (as a normal tyre would) - this then leads to slow punctures, further tyre deformation (even with a small bulge, replacement will become a necessity sooner rather than later), or in the worst cases, a requirement for immediate replacement.

I live in a rural area with very poorly maintained roads, many of which have been 'dressed' multiple times (with no accompanying attention to drains, turning them into 4"++ deep hazards) and which have multiple other holes, cracks,etc. The roads are narrow, typically NSL, very twisty, with aforementioned hazards often sited immediately after blind bends. Unless you drive everywhere at 20mph, you WILL hit one of these when you go round one of these corners and a car is coming the other way, so no way to avoid....

Dunlop Sport Maxx GTs are not cheap - and I've just replaced my third off-side front in 2 years...

So the cost of swapping them when the car is new perhaps could be off-set by likely replacement costs you'd face if you didn't, and you get a better car in the interim. Sure someone can do the man-maths on that...

Then of course there are the brake pads, which at 11k miles now need replacing...

Love the car for so many other reasons, but won't be going anywhere near another!

[sinly]

Morning! All 4 20" RF tyres will be needing replacement soon on my 640 and given price and ride issues now thinking of non RF especially after reading some experiences on here 👍

Concerned about and BMW warranty issues as can imagine OPC will recommend the original spec tyres....also any issues with warning lights etc!? Anyone also know if BMW assist would attend if had a puncture and changed tyres for non RF or would need to join inde breakdown for peace of mind?

Any advise on this please!?...thanks.

[Monty Python]

sinly said:

Morning! All 4 20" RF tyres will be needing replacement soon on my 640 and given price and ride issues now thinking of non RF especially after reading some experiences on here ??

Concerned about and BMW warranty issues as can imagine OPC will recommend the original spec tyres....also any issues with warning lights etc!? Anyone also know if BMW assist would attend if had a puncture and changed tyres for non RF or would need to join inde breakdown for peace of mind?

Any advise on this please!?...thanks.

According to the documentation they won't attend a puncture, just advise you on how to use the mobility kit that's supplied with the car.

After all, if you change the car from the manufacturer's original specification you can't expect them to help you out since the problem is of your making.

[anonymous-user]

had ham said:

I have RFTs on 20" on my 640d GC, and have driven a similar car with non-RFTs and it was immeasurably better.

Another major issue with RFTs, particularly on the 20s is that they don't react very well at all to hitting pot-holes, and the side walls tend to fold and bulge rather than bounce back (as a normal tyre would) - this then leads to slow punctures, further tyre deformation (even with a small bulge, replacement will become a necessity sooner rather than later), or in the worst cases, a requirement for immediate replacement.

I live in a rural area with very poorly maintained roads, many of which have been 'dressed' multiple times (with no accompanying attention to drains, turning them into 4"++ deep hazards) and which have multiple other holes, cracks,etc. The roads are narrow, typically NSL, very twisty, with aforementioned hazards often sited immediately after blind bends. Unless you drive everywhere at 20mph, you WILL hit one of these when you go round one of these corners and a car is coming the other way, so no way to avoid....

Dunlop Sport Maxx GTs are not cheap - and I've just replaced my third off-side front in 2 years...

So the cost of swapping them when the car is new perhaps could be off-set by likely replacement costs you'd face if you didn't, and you get a better car in the interim. Sure someone can do the man-maths on that...

Then of course there are the brake pads, which at 11k miles now need replacing...

Love the car for so many other reasons, but won't be going anywhere near another!

I'm sorry but there's no evidence at all for most of what you've said. If you have any real issue its stupidly low profile tyres of any ilk but perhaps if you looked where you're going and drove appropriately you wouldn't suffer as you do. Brake pads at 11k? Really?

I live out in the country and we have as many narrow, potholed lanes as anyone else but haven't had a puncture or damaged tyre or wheel in the 6 years we've been here. RFT or otherwise.