Changing from run flats to conventional tyres

Changing from run flats to conventional tyres

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Discussion

johnao

Original Poster:

672 posts

249 months

Friday 16th October 2009
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I'm about to replace my BMW 335i Bridgestone Potenza RE050A run flat tyres with conventional tyres (I've almost overcome my fear of having no spare tyre). The run flats produce a very harsh and extremely crashy ride. The tyres are (front) 225/45R17 91W and (rear) 255/40R17 94W. The consensus seems to be a choice between Goodyear Eagle F1 Asymmetric or Michelin Pilot Sport PS2.
Does anyone have any positive or negative feedback about either the Goodyear or Michelin tyre? Are there any other tyres that anyone would recommend? Does anyone suggest that I stick with the Bridgestone run flats or can recommend another run flat with a better ride than the Bridgestones.

All comments gratefully received.

Many thanks

Neil.D

2,878 posts

212 months

Saturday 17th October 2009
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Both are excellent - I have had both. If you have money to burn I would suggest the PS2's. The F1's are excellent but tramline a touch more I have found. I cannot fault the wet grip with them either. The F1's will be about 2/3'rds the price of the PS2's.

You will not find a better tyre than the PS2 which offer great feedback and amazing levels of grip.

Neil.D

loomx

327 posts

231 months

Monday 19th October 2009
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Another tyre worth looking at is the Vredestein Ultrac Sessenta. They are brilliant, and outstanding in the wet!

jarnold88

843 posts

185 months

Monday 19th October 2009
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Check out the Uniroyal Rainsport 2 tire.

ive got them on my car ans the FunCup series uses them, they are brilliant tires, especially in the wet, as it is a rain tire, and good in the dry too - mega grip, very good on wear, great feedvack through the tire and theyre reletively cheap too smile

J

dom180

1,180 posts

270 months

Monday 19th October 2009
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2 years is a long time as far as tyre lifecycles/development is concerned - the following review may be of interest.

http://www.tyrereviews.co.uk/Article/2009-Auto-Zei...

Bear in mind different tyres suit fwd/rwd more or less but there have been several positive reports from different sources on the new P-zeros and Lotus selected them for the Evora.


blueg33

38,026 posts

230 months

Monday 19th October 2009
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loomx said:
Another tyre worth looking at is the Vredestein Ultrac Sessenta. They are brilliant, and outstanding in the wet!
+1

Make my previous Pirelli Pzero Rosso's seem like ice skates

RobM77

35,349 posts

240 months

Wednesday 21st October 2009
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I've just bought a BMW with run flats and was wondering what I'd do at tyre changing time because I prefer the feel of normal tyres. Does anyone have any comments on the effect on the overall suspension by changing the tyre? Obviously when the springs and dampers are tuned it has to to take account of the tyre sidewall, which is in effect an undamped spring. Run flats are hugely stiffer than ordinary tyres, and as such it'll have an effect on the overall suspension as intended by the manufacturer. Should I worry about this? (I'm really picky about ride and handling!).

thequietone

170 posts

207 months

Wednesday 21st October 2009
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For cars supplied by the manufacturer with run-flats (I have 1 series sport with 'em) the damper rates are tuned for the tyres. If you swap your run flats for conventional rubber you will get the 'feeling' back in the steering. If you car (BMW) has big wheels (17&18") the difference will be slightly less noticable as the low pro tyre and higher pressure will be a smaller difference than the stiff wall of the run flat.
If you drive in a 'spirited' fashion you will knacker the front edges really quickly with the run flats so the change may come fairly quickly!!

You'll not regret changing - unless you get a puncture.

Edited by thequietone on Wednesday 21st October 13:06

RobM77

35,349 posts

240 months

Wednesday 21st October 2009
quotequote all
thequietone said:
For cars supplied by the manufacturer with run-flats (I have 1 series sport with 'em) the damper rates are tuned for the tyres. If you swap your run flats for conventional rubber you will get the 'feeling' back in the steering. If you car (BMW) has big wheels (17&18") the difference will be slightly less noticable as the low pro tyre and higher pressure will be a smaller difference than the stiff wall of the run flat.
If you drive in a 'spirited' fashion you will knacker the front edges really quickly with the run flats so the change may come fairly quickly!!

You'll not regret changing - unless you get a puncture.

Edited by thequietone on Wednesday 21st October 13:06
That's interesting. The only thing I don't like about the new car I'm picking up tomorrow is that the electric PAS doesn't offer much feel. Are you saying that there's a chance I'll get more steering feel with normal tyres? smile

thequietone

170 posts

207 months

Wednesday 21st October 2009
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I've not changed the tyres on the BMW but had run flats on a Mini a few years ago that were changed to 'normal' rubber.
I find the run flat tyres hinder the ability to judge just how hard you are leaning on them and the chassis - they give the same feeling during turn-in at both low speed/load situations and high speed/load situations. Once I changed the tyres on the Mini, you could 'feel' for the grip again. The difference is magnified in the cold/wet/damp months where I find the RF's just cant find the grip.

Of course, run-flats only really work when used with the ABS and rev limiter school of braking which combined, give massive grip on the way into your favorite roundabout. laughbiglaugh

RobM77

35,349 posts

240 months

Wednesday 21st October 2009
quotequote all
thequietone said:
I've not changed the tyres on the BMW but had run flats on a Mini a few years ago that were changed to 'normal' rubber.
I find the run flat tyres hinder the ability to judge just how hard you are leaning on them and the chassis - they give the same feeling during turn-in at both low speed/load situations and high speed/load situations. Once I changed the tyres on the Mini, you could 'feel' for the grip again. The difference is magnified in the cold/wet/damp months where I find the RF's just cant find the grip.

Of course, run-flats only really work when used with the ABS and rev limiter school of braking which combined, give massive grip on the way into your favorite roundabout. laughbiglaugh
rofl

There was less chassis feel in the car I'm buying (Z4 coupé) than I'm used to in cars as a rule actually. I didn't notice the problem that my Dad's 320d has though - that of a crashy ride. Somehow the run-flats suited the suspension in the Z4 better.

I've not heard anything but criticism for run-flats. I wonder why BMW persist with them?

thequietone

170 posts

207 months

Wednesday 21st October 2009
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The lack of feedback at the wheel could be down to the electro hydraulic steering? I remember thinking the weighting was a little il-judged. This was a good few years ago though and I'm sure BMW will have revised the system on the later cars.
Cracking motor car though.

RobM77

35,349 posts

240 months

Wednesday 21st October 2009
quotequote all
thequietone said:
The lack of feedback at the wheel could be down to the electro hydraulic steering? I remember thinking the weighting was a little il-judged. This was a good few years ago though and I'm sure BMW will have revised the system on the later cars.
Cracking motor car though.
Yes, that's what it is. The M version has hydraulic PAS, which solves the problem. It's the only downside of an otherwise great car. I don't think BMW ever revised the system, and of course they no longer make them (having reverted to a heavier folding hard top Z4 instead). My Z4 coupé ("My" as of tomorrow that is!) does have a "Sport" button to reduce the assistance on the steering wheel, but I remember noting on my test drive that the steering was still nowhere near as good as the E36 328i that I've just sold.

istoo

2,365 posts

208 months

Wednesday 21st October 2009
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I have just done this with our 530d E61 as well. But i did hear BMW will sell a spazsaver. I kept back one good runflat tyre with the intention of buying a sdare MV2, but it doesn't fit in the foot well!

Only comment is that I have added 2psi all round to the tyre setup to compensate for the really thick side walls on the runflats. As it felt too soft on the front especially. So 36psi front and 40psi back.

johnao

Original Poster:

672 posts

249 months

Wednesday 21st October 2009
quotequote all
istoo said:
I have just done this with our 530d E61 as well. But i did hear BMW will sell a spazsaver. I kept back one good runflat tyre with the intention of buying a sdare MV2, but it doesn't fit in the foot well!

Only comment is that I have added 2psi all round to the tyre setup to compensate for the really thick side walls on the runflats. As it felt too soft on the front especially. So 36psi front and 40psi back.
What tyres have you used in place of the runflats?

Thanks to everyone for the feedback.

RobM77

35,349 posts

240 months

Wednesday 21st October 2009
quotequote all
istoo said:
I have just done this with our 530d E61 as well. But i did hear BMW will sell a spazsaver. I kept back one good runflat tyre with the intention of buying a sdare MV2, but it doesn't fit in the foot well!

Only comment is that I have added 2psi all round to the tyre setup to compensate for the really thick side walls on the runflats. As it felt too soft on the front especially. So 36psi front and 40psi back.
Hmm.. that kind of confirms my fears about messing the suspension settings up.

dom180

1,180 posts

270 months

Wednesday 21st October 2009
quotequote all
RobM77 said:
istoo said:
I have just done this with our 530d E61 as well. But i did hear BMW will sell a spazsaver. I kept back one good runflat tyre with the intention of buying a sdare MV2, but it doesn't fit in the foot well!

Only comment is that I have added 2psi all round to the tyre setup to compensate for the really thick side walls on the runflats. As it felt too soft on the front especially. So 36psi front and 40psi back.
Hmm.. that kind of confirms my fears about messing the suspension settings up.
Good excuse to upgrade to M-coupe springs/dampers - that didn't have run flats.

RobM77

35,349 posts

240 months

Wednesday 21st October 2009
quotequote all
dom180 said:
RobM77 said:
istoo said:
I have just done this with our 530d E61 as well. But i did hear BMW will sell a spazsaver. I kept back one good runflat tyre with the intention of buying a sdare MV2, but it doesn't fit in the foot well!

Only comment is that I have added 2psi all round to the tyre setup to compensate for the really thick side walls on the runflats. As it felt too soft on the front especially. So 36psi front and 40psi back.
Hmm.. that kind of confirms my fears about messing the suspension settings up.
Good excuse to upgrade to M-coupe springs/dampers - that didn't have run flats.
I'll check tomorrow, but I think my car's got a sports suspension upgrade. I wouldn't want to put something on the car that it wasn't designed to take; the ARBs, geo and weight will all be different.

dom180

1,180 posts

270 months

Wednesday 21st October 2009
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Actually a quick google shows that the M car's suspension is quite a lot different to the Coupe and not interchangable, so not a good idea!

skeeterm5

3,588 posts

194 months

Thursday 22nd October 2009
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my wife changed the RFT to normal on her mini cooper and it absolutely transformed the car - best mod ever!

S