[m_star01]

I know this is a question is a silly one, but if I change to normal tyres from run flats do I need to ask the fitter to change any sensors or my suspension settings? My thinking is if the car was designed with RFs surely something needs to change?

[Sam_M]

No nothing.

The suspension may feel softer as it was designed to be used with solid sidewalled runflats but you don't need to change anything.

[therealdb1]

No just fit the normal tyres and drive off with a smile on your face.
They will transform the ride of the car!

[m_star01]

Even if I have m sport car? My rears are 225/35/18

When we talk about soft are we saying I feel a lot more bumps on the road?

[AD18]

Originally Posted by m_star01

When we talk about soft are we saying I feel a lot more bumps on the road?

I'd like to know this too. I just changed all 4 to non run flats but I'm getting shaking through the seat and wheel at 70mph. I had the wheels rebalanced at a different place and 4 wheel alignment done just now but no difference. Can't think what it would be.

[Kjb1]

Possible guibo?? Are presures ok on tyres?? Is it just under braking? Or all time? If when braking your rear disks are warped.

[AD18]

Originally Posted by Kjb1

Possible guibo?? Are presures ok on tyres?? Is it just under braking? Or all time? If when braking your rear disks are warped.

Its at 70mph-ish when it starts which led me to believe its tyre wheel balancing which needs doing. Did balancing and 4 wheel alignment today with the hope that would solve it, but it hasn't...

[m20b25]

I have exactly same problem after swapping from run flats. Smooth as butter then hit 70 and get vibration through the floor and seat. Braking and corners don’t make a difference and it disappears around 100.

I’ve changed all front bushes and ball joints. New tyres all round, new dampers, springs, top mounts and bump stops. Didn’t just change these to fix the problem, it all needed doing anyway.

Thinking it’s drive train related: guino, gearbox & engine mounts (gearstick bounces a bit over bumps)

[Sam_M]

Originally Posted by m_star01

Even if I have m sport car? My rears are 225/35/18

When we talk about soft are we saying I feel a lot more bumps on the road?

No, the opposite. It’ll probably feel more compliant. The tyres will eat more road imperfections than before.

[m_star01]

Thanks for the advice, just concerned with the people on here who have changed from RFs to normal tyres, why do they get issues driving 70mph weird and worrying

[therealdb1]

If the vibration at 70 mph was not there before the tyre change and it is after the tyre change the problem is wheel balance.

The guys with problems do not say where they got their tyres fitted but consider that a lot of tyre shops employ sometimes young and inexperienced fitters because they are cheap and they can make mistakes because they are often poorly trained. I once had an exhaust fitted at one of the most well known major chains and the manifold to downpipe flange should have had 6 bolts. Because the lad, I cannot call him a fitter, had used his air tool to fit 5 of the bolts the hole for the 6th was slightly out of alignment and he could get the last bolt in so he threw it in the bin and was happy for me to drive away with my car like that! It was only because I could see he was struggling and he appeared to deposit something in the bin that I checked under the bonnet before I took the car away. Needless to say I "consulted" the branch manager who appologised and got someone twice the age of the original person to bolt the pipes up properly. To me it would have made sense to get the lad to watch how to do the job but they chose to miss that opportunity and just let him get on with the next job.

For example, if we are talking 18" alloys you would expect all balance weights to be of the stick on variety on the inside rim of the wheel. This is usually the dirtiest part of the wheel because of all the brakedust and general road grime collects here unless the owner is particularly fastidious and removes the wheels each time he washes the car! If this area is not cleaned and spotless before the weights are stuck on they probably cling on for long enough for the fitter to "balance" the wheel but may fly off the moment you hit a bump in the road in the real world.

I suspect that a majority of E9x's are not on run flat tyres anymore but we do not all suffer vibrations.

Moral of the story is don't just go to the most convenient or cheapest place but pick a tyre fitter that is used to the sort of wheels that we have, properly trains their staff and employs people that are concientious enough to do the job properly.

Of course, if the vibration has been persistent and is not a result of the tyre change then it is an entirely different scenario and could be engine / gearbox mounts or propshaft issues.

[therealdb1]

Originally Posted by m20b25

Thinking it’s drive train related: guino, gearbox & engine mounts (gearstick bounces a bit over bumps)

This is a clue, isn't it?

Gearbox moving around over bumps is not because you have changed your tyres!

Lift the car off the ground and push on the side of the gearbox. If you can move it at all then you need to look around for the knackered mounting but don't forget it could be one of the engine mounts.

Do this sooner rather than later and remind me not to be a passenger if you drive at 100 mph knowing that there is a drivetrain problem!

[therealdb1]

Originally Posted by AD18

I'd like to know this too. I just changed all 4 to non run flats but I'm getting shaking through the seat and wheel at 70mph. I had the wheels rebalanced at a different place and 4 wheel alignment done just now but no difference. Can't think what it would be.

Are you sure it did not do this before you replaced the tyres?

From memory I don't think you have had this car long, have you?

It could be a drive train problem that you have only noticed since the new tyres went on so they get the blame.

[tcphoto]

I recently went from Michelin Run Flats to PSS4’s and am very happy with them. You should not have any issues if they are properly balanced and aligned, the sensors are mounted on the wheels. I find the car handles a little better, rides slightly softer than Run Flats and MPG is slightly better on the first three tanks of gas.

[m_star01]

Great advice here thanks.

Some questions...

1. Do insurance companies possibly call this a modification and price accordingly?

2. My rears are 255/25/18 fronts 255/40/18 getting normal tyres my worry is having puncture In will make me call the AA. Or get a tyre repair kit. What's the real world claims how far can you drive with a RF I mean it can't be repaired so it's pointless unless u need to move away from main road or a blow out I guess

3. Seeing comments here it seems the ride be better and I won't feel all the bumps which is a bonus and a plus point.

4. Should one get the same sizes I have for winter tyres or I can differ?

[Maxlude]

If there was no vibration before new tyres then it's most likely the balancing. I just had my alloys fully refurbished and balanced from a place I'd never been to before yet, when got car back, it started to shake itself to bits once over 65mph when it was fine before.
So I took to a place I'd been to before for new tyres and did good balancing. When I got it back all the vibration was gone but I noticed that this place had stuck the weights on almost the opposite side of the refurb place!!! So looks like the refurb place operator did not know what they were doing.
You can also try on car or road force balancing.

[therealdb1]

Originally Posted by Maxlude

When I got it back all the vibration was gone but I noticed that this place had stuck the weights on almost the opposite side of the refurb place!!! So looks like the refurb place operator did not know what they were doing.
You can also try on car road force balancing.

My point exactly! Even if they have the latest electronic balancing wizardry it still relies on the human element to get it right and the larger the wheel in rolling diameter and width the better it needs to be.

I did have an Opel Manta once that gave no end of problems with wheel balance and the only way I could get it satisfactory was to have the wheels balanced on the car. Downside to this is if you take the wheels off for any reason they must go back on in exactly the same orientation on the same hub to retain the balance.

Frankly I thought on car balancing was old hat with the machines around today but as a last resort it might be worth seeking out someone who can do it.

[therealdb1]

Originally Posted by m_star01

Great advice here thanks.

Some questions...

1. Do insurance companies possibly call this a modification and price accordingly?

2. My rears are 255/25/18 fronts 255/40/18 getting normal tyres my worry is having puncture In will make me call the AA. Or get a tyre repair kit. What's the real world claims how far can you drive with a RF I mean it can't be repaired so it's pointless unless u need to move away from main road or a blow out I guess

3. Seeing comments here it seems the ride be better and I won't feel all the bumps which is a bonus and a plus point.

4. Should one get the same sizes I have for winter tyres or I can differ?

1. Who fits OE tyres anyway? Once the car is as old as a E9x is now you probably can no longer obtain the OE tyres.
If you are concerned about the insurance call your company and tell them. If they try and charge you a premium find a new insurance company. My company did not charge me a premium for advising them that I had 19" alloys fitted. Provided they know it is no problem.

2. Run flats were fitted for one purpose. It is to avoid having a spare wheel and not for driver convenience!
Think about how many miles you have driven in the last year, five years, ten years, how many punctures have you had which has stopped the car in its tracks?
Get yourself a mini compressor and some gunk or rely on your chosen rescue service.

3. The ride will be transformed for the better. You will soon forget your worries and wish that you had made the change sooner.

4. It says you are in London. London does not have winters and I lived there for 45 years. Normal tyres will do all year round provided that in the unlikely event there is a snowflake or hailstone on the road you drive accordingly.

[m_star01]

Well not sure why the dealer when i went to service my car, guy on the desk said "the car is designed for RFs as BMW tuned the suspension for it, if you change then the results are unknown may affect the drive, economy and suspension, dampers etc etc"

thanks why i asked not sure if he was right.

[Maxlude]

Standard suspension on E9x was rubbish anyway. You can use XL rated normal tyres which have reinforced sidewalls that will behave more like rft but still be more forgiving than rft

[therealdb1]

Originally Posted by m_star01

Well not sure why the dealer when i went to service my car, guy on the desk said "the car is designed for RFs as BMW tuned the suspension for it, if you change then the results are unknown may affect the drive, economy and suspension, dampers etc etc"

Absolute tosh!

The reason the dealer wants you to keep with run flats is because he wants to sell you a set at an inflated (pun not intended!) price rather than ordinary tyres that mere mortals drive on.

I am surprised BMW do not get a tyre manufacturer to brand tyres with a BMW roundel on the wall then they could really charge you through the nose!

Jaguar tried a similar theme once and claimed that XJ6 (X300) suspension was developed in conjunction with the then "revolutionary" Pirelli P6000. It wasn't until drivers started fitting alternative tyres that they realised that in fact they could improve the ride, the noise level, braking and cornering performance.

[Donnie2000]

My experience switching to standard eagle f1's was horrendous understeer. It was there with the rft potenzas but not nearly as bad. A lack of camber and a soft sidewall seem to contribute. You can see the extreme wear and marking on the sidewall of the tyre. Adding some front and removing some rear camber has helped immensely but I'm sorry I didn't go for a square or closer to square tyre set up. I have the standard 225 255 set up on 19's. I think a set of 245 all around might be a better balance.