Mixing runflats and standard tyres
Mixing runflats and standard tyres
Author
Discussion

kojak

Original Poster:

4,547 posts

283 months

Saturday 7th May 2011
quotequote all
Am i ok to change my rear tyres to standard tyres while keeping runflats on the front....until they need changing?

Heathwood

3,036 posts

232 months

Saturday 7th May 2011
quotequote all
Not a good idea at all as I understand it.

The Stiglet

2,063 posts

224 months

Saturday 7th May 2011
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Can't see that working. Surely different tyre pressures, profile depths, contact patches and different ride/handling characteristics makes for some unsettled and perhaps dangerous driving?

All or nothing IMHO.


gizlaroc

17,251 posts

254 months

Saturday 7th May 2011
quotequote all
No, change all 4 to non run flats.

A tyre like the Kumho KU31 will trounce even the best run flat in every department and will cost less for 4 than 2 new run flat rears.

newberry

513 posts

228 months

Saturday 7th May 2011
quotequote all
Mine has run flats on the back and normal on the front and seems ok, and I'm not dead yet either.

kojak

Original Poster:

4,547 posts

283 months

Saturday 7th May 2011
quotequote all
The Stiglet said:
Can't see that working. Surely different tyre pressures, profile depths, contact patches and different ride/handling characteristics makes for some unsettled and perhaps dangerous driving?

All or nothing IMHO.
Would that be a problem!! Sometimes tyres have different pressures front and rear. Tread pattern will change anyway if you put different makes of tyre on the front compared to the back. Could do with not paying for 4 tyres,

Raify

6,556 posts

278 months

Saturday 7th May 2011
quotequote all
I did it for a short time, whilst waiting for the next nail to turn up in the run flats.

It's not dangerous, but not ideal either. The proper tyres will have a massively grip level than the run flats. I ended up in a four wheel drift around a greasy roundabout at very low speed. Straight after that I dumped the other 2 runflats.

cervelo

53 posts

211 months

Saturday 7th May 2011
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had the same question a few months ago. after much discussions with my bmw mechanic i put non run flats on the front, as only these needed changing. 21" bmw wheels on a new x5 sd, 285 35's.

so much better and less crashy and no problems at all. but obviously its not a car thats thrown around.

i changed all 4 on my cooper s to non run flats and again so much better.


liquidken

1,816 posts

271 months

Saturday 7th May 2011
quotequote all
newberry said:
Mine has run flats on the back and normal on the front and seems ok, and I'm not dead yet either.
If you have tpms fitted then its not so bad. If you don't, you're running a big risk.

Either way, the mix of tyres will shift the balance and feel of the car quite a bit which is far from ideal.

StuB

6,695 posts

269 months

Saturday 7th May 2011
quotequote all
Runflats on my E60 530d refused to wear out, but the rears were changed to ZZ3's and there were no issues at all with the car's handling/balance.

Have new generation RFT's on my F11 touring and don't like them either.

Steff

1,421 posts

293 months

Saturday 7th May 2011
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as long as you change the axle set a time then there's no issue in my experience.


BJT

2,344 posts

277 months

Sunday 8th May 2011
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The way I see it:

Big expensive car, priceless occupants and other road users about.
The Tyres are the only things that stick the car to the road, why take a risk? Get new ones all around and then flog the part worn ones on eBay.
From my experience with the Z4, ditching the runflats was the best decision I made.

christer

2,804 posts

281 months

Sunday 8th May 2011
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kojak said:
Am i ok to change my rear tyres to standard tyres while keeping runflats on the front....until they need changing?
Absolutely not. Imho, dyor

ccr32

1,984 posts

248 months

Monday 9th May 2011
quotequote all
BJT said:
The way I see it:

Big expensive car, priceless occupants and other road users about.
The Tyres are the only things that stick the car to the road, why take a risk? Get new ones all around and then flog the part worn ones on eBay.
From my experience with the Z4, ditching the runflats was the best decision I made.
Does anyone actually buy part-worn tyres on ebay? If so, I'd consider changing all 4 of mine, but if not I begrudge doing that now seeing as I've only done about 2000 miles on the current (RFT) rears.

Also, has anyone had to deal with the BMW Insured Warranty people having changed RFT's for non-RFT's? Last time I asked, I was advised that doing so may well void the warranty that I'd just shelled out to renew...

Magnus Barelegs

106 posts

191 months

Monday 9th May 2011
quotequote all
Raify said:
I ended up in a four wheel drift around a greasy roundabout at very low speed. Straight after that I dumped the other 2 runflats.
So you went into a four wheel drift, but you're blaming the two runflats for it?
If you went into a four wheel drift, looks like all four tyres lost grip at the same time.
Therefore, no difference in grip between your runflats and non-runflats.
My opinion on the subject is that the average driver won't notice any difference.
So if they can't afford it, don't do it.




Edited by Magnus Barelegs on Monday 9th May 11:08

Raify

6,556 posts

278 months

Monday 9th May 2011
quotequote all
Magnus Barelegs said:
So you went into a four wheel drift, but you're blaming the two runflats for it?
If you went into a four wheel drift, looks like all four tyres lost grip at the same time.
Therefore, no difference in grip between your runflats and non-runflats.
My opinion on the subject is that the average driver won't notice any difference.
So if they can't afford it, don't do it.




Edited by Magnus Barelegs on Monday 9th May 11:08
Yes, because under normal circumstances, the FWD car they were attached too would have understeered first. Even though both sets of tyres had comparabable tread depths, the rears let go as if they were near the markers (exacltly like it did on 4 normal tyres with wear markers showing on the rears).

Therefore, the runflats had different levels of grip.



Magnus Barelegs

106 posts

191 months

Monday 9th May 2011
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anonymous said:
[redacted]
Again, that isn't a problem at all.
I've had cars where every tyre has had a different tread pattern.
Because it was on full maintenance and I didn't get a choice from the leasing company.
All the same make (Pirelli) and all the same size/speed rating/load rating.
But different types, and therefore tread patterns, all round.
Not a problem, and whilst I wouldn't claim to be the fastest driver around I do drive faster than average.
Tread patterns are as much about fashion as anything else.
Michelin employ full-time tread designers.
Not to make the tread work, but to make them look attractive!!!

Vladimir

6,917 posts

188 months

Monday 9th May 2011
quotequote all
I changed all mine at once (from RFTs to non RFTs) even though the fronts still had a fair bit of tread. I couldn't wait to get them off!

I always match tyres and always have done.

phumy

5,828 posts

267 months

Tuesday 10th May 2011
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There is also the subject of carrying a spare if you have non RFT's, plus the added complication of running with different sized wheel/tyres from front to rear (on certain cars) so two spares required.

parapaul

2,828 posts

228 months

Tuesday 10th May 2011
quotequote all
Or a can of tyre weld, a small compressor and no spare?