run-flats vs regular tyres

[pk328]

Thinking of buying a Z4 Coupe but I'm getting seriously put off by talk of its hard ride and tramlining on run-flats.

Does anyone know if its OK to switch to some good spec normal tyres or is the suspension geometry set up specifically for run-flats?

Also, do dealers have to supply them with run-flats or can you swith to normal ones at the time of order?
Cheers.

[speedyz4]

hi there yes RF are hard ride and living usa FL it rain alot the Rf suck when its wet
and they wear fast so i have a spare tire kit from leather z.
replaced the RF with goodyear f1 AA wet or dry 150.00 us .

[bindit]

I presume that all four runflats have to be replaced at the same time?

Was thinking about this for my M3, not sure if it is worthwhile though.

[m3desmo]

Forget using run-flats. Shite ride quality and handling is affected due to higher unsprung weight. Just stick with the Pilot Sport 2 on the M3. Originally had Pilot Sport 1 on the car, but the 2's are much better.

[bindit]

m3desmo said:

Forget using run-flats. Shite ride quality and handling is affected due to higher unsprung weight. Just stick with the Pilot Sport 2 on the M3. Originally had Pilot Sport 1 on the car, but the 2's are much better.

I would have thought the increased sidewall rigidty would affect the handling more than a couple of pounds of extra weight per corner?

Is it possible to replace the rears with non-runflats, keep run flats on the front? Hmmm, doesn't too viable now i think about, but you never know..

[anonymous-user]

Corvettes have been blighted by run-flats for years. We find switching to conventional tyres gives very significant improvements in both ride and handling. Michelin Pilot Sports are a popular conversion - they ain't cheap but they're very good.

Personally I would have thought having such significantly different tyres on front and back could be a serious mistake. I've never heard of anyone changing just one end of the car. It could give very strange or even dangerous handling characteristics.

Edited by 5 USA on Tuesday 12th September 10:55

[M3desmo]

bindit said:

m3desmo said:

Forget using run-flats. Shite ride quality and handling is affected due to higher unsprung weight. Just stick with the Pilot Sport 2 on the M3. Originally had Pilot Sport 1 on the car, but the 2's are much better.

I would have thought the increased sidewall rigidty would affect the handling more than a couple of pounds of extra weight per corner?

Is it possible to replace the rears with non-runflats, keep run flats on the front? Hmmm, doesn't too viable now i think about, but you never know..

You are right that it is only a few pounds of extra weight at each corner with run-flats but crucially it is unsprung weight and ask any handling 'guru' and they will all say that this is where you should look to save weight!! Cheap aftermarket alloys are almost always heavier than factory OEM alloys and also cause similar problems with increased unsprung weight.

For the extra that it costs to change all tyres (a full set works out cheaper per tyre) why would you want to compromise the handling or ride quality by just changing the rears? If the car was a little Corsa or such like then maybe, but an M3 is a performance car and the tyres are the bits that keep you stuck to the road at the end of the day! Why risk a valuable car by cutting corners (pardon the pun) on the tyres?? On a RWD car like the M3 a general 'rule of thumb' is that you will use 2 sets of rears for each set of fronts, depending of course on how you drive!

Run-flats were designed pure and simply for nobheads who never check the oil, tyre pressures or any other part of their car for that matter (they probably don't even know how to open the bonnet!) and contribute nothing to the dynamics of the car! Just an opinion but I know that I will always install a full matched set of the best tyres that I can afford to my car.