swapped runflats for non RF now E61 has lots of body roll

[yodamode]

OK i checked out all the posts on PH and it seems pretty much agreed that swapping the factory supplied runflats for non runflats is a perfectly OK thing to do. Potentially getting a smoother ride and saving about 30% on the cost of tyre replacements, so that's what i done.. However.... I have only swapped the rears (for a-symentrical Michelin Eagle F1's) with the fronts still being runflats (Michelin NCT 5's).

At the same time I has the tracking fixed as it was way out on the rear and OK, but still out on the front. This also resulted in my off center steering wheel now being nicely centered. All was good off I drove into the sunset.

The thing is now the car has significantly more body roll than before. The wife noticed it straight off and said it felt unsafe without me mentioning I had picked up on any change.

Anyhow I am unsure where to go from here. Based on previous searched the concept of using non-runflats seems sound, but do I now have to swap the fronts as well? Should I get the tracking/pressures checked???

I've got 32psi rear and 30psi front.

i'm thinking now though that those quoted pressures on the door shut are for RF's so maybe they need to be tweaked..

Any tips on suggested tyre pressures, or simply if it's a bad idea to mix the tyre types would be very much appreciated,

Cheers

[The real Apache]

The sidewalls in RFTs are very hard so you will feel a difference but with a mix? not sure I'd want to do that

[gizlaroc]

Firstly I really wouldn't mix run flats with non run flats, and I wouldn't mix a symmetrical tyre with an asymmetrical tyre, although putting the asymmetrical one on the rear is the better bet and is done when you want to promote over steer, putting an asymmetrical on the front is just seriously dangerous and all tyre manufactures will tell you not to do it.


You need to get the tyres matching, I had 3 days with PS2s on the rear of my 535d sport touring with the Brickstone run flats on the front and it was pretty scary how twitchy it became.

Also put the rears up to 36-38psi with proper tyres on, that will help a little and is the correct pressure.

[gizlaroc]

Also, did you make sure you bought the XL tyre, you need the one that is the correct stiffness sidewall for the rather heavy 5er touring, but the tyre centre should have made sure of this.

[KnockinShop]

I just changed from RunFlat to Non-Runflat. Had planned to just do 2 tyres, but got serious warnings about it.
Was told that the car would handle like the non-runflats were flat tyres.
You may have to switch the other 2. But if the runflats are in good condition, you may be able to sell them second hand.
Also, 30/32 is quite low. About 36 or above is normally needed. Post tyre sizes for more info.
I've 245 40 18 and was recommended 36 front and 34 rear, although think maybe I should have more than this.

[Great Pretender]

gizlaroc said:

Also, did you make sure you bought the XL tyre, you need the one that is the correct stiffness sidewall for the rather heavy 5er touring, but the tyre centreshould have made sure of this.

And there in lies the problem I suspect.

[yodamode]

OK, thanks everyone. First of all ref most recent post, the new tyres thankfully do state 'Extra Load' on the side wall so I'm assuming they are OK then. The sizes are as follows: FRONT - 245/40 R18 93Y (RF's) REAR - 245/40R18 97Y (Non-RF's)

If anyone does know the best tyre pressure to use for this combo that would be great, and if it still feels like I am out on the Norfolk broads on a day cruiser I think I better bite the bullet and order 2 new matching asymmetric's for the front.

Cheers.

[gizlaroc]

Are they not staggered??
If it we me I would put 265/35/18 on the rear and move those to the front.

Those tyres need aroun 36 to 38 psi for normal loads.

[phelix]

So long as the 245/40 18s have a load value of 93 or higher they'll be fine, RFT or conventional.

I would run the factory pressures (32F, 39R) plus or minus a max of 10 percent. Running a low profile tyre on too low a pressure will cause the tread to balloon at speed resulting in high tread wear in the centre. As the tyre will move around on the rim more under cornering. Try 39 psi and see how it feels.

[Luvmyzed]

Cripes,mixing run flats and non runflats, you're a brave man!! I'd never do that,it's a lethal combo.Probs why the car feels really sh*t.It'll feel softer for sure with non runflats but shouldbe much better,and also make sure they're not too soft.Good luck.

[Ranger 6]

yodamode said:

The sizes are as follows: FRONT - 245/40 R18 93Y (RF's) REAR - 245/40R18 97Y (Non-RF's)

OK, you've commited the cardinal sin of mixing RFT and non-RFT tyres. Also the load index is different(the Y rating).

It doesn't matter that the tyres are not staggered the handling issues and wallowing is because you've got stiff sidewalled RFTs on the front with a heavy construction normal tyre on the back. All of them will be working against each other and that's the instability you are feeling.

So, simply swap the fronts immediately!

[yodamode]

OK. I have taken heed to the warnings.. same exact type/size has been ordered for both fronts. Going on tomorrow.

I had upped pressures which made it feel better at low speed but at 80mph she kind of has a will of her own :0


One other thing my tyre dude mentioned is that is there is still a prob i should get the camber checked since he did not have the tool on the van so couldn't check that at the same time a the tracking.

I will post an update tom.

[Ranger 6]

Phew!! excellent choice

You'd be suprised how sensitive BMWs can be to tyres - have a look round as M3s in particular have issues if they've got different brands at each end.

[Pickled Piper]

Have a look on the Michelin website and contact their tech department. They will be able to give you full details on tyre pressures and also sizes and types etc.

pp

[HellDiver]

yodamode said:

(for a-symentrical Michelin Eagle F1's) with the fronts still being runflats (Michelin NCT 5's).

I think you mean Goodyear.

[yodamode]

OKdokey.. standard tyres now on all corners. found that one of the front wheels has a 1 inch crack on inside of rim (a knows fault with bimmer wheels apparently) and a small bulge on tyre.

trying to decide if its advisable to get it welded as finding it hard to find a replacement original wheel (dont want 4)..

I have attached a pic of the crack.

handling: she is was better now but not sure if she is 100% so off to get her tracked today.
weld it or bin it???

[Brewsters]

Nasty crack - personally I'd bin it.

[bluetone]

Brewsters said:

Nasty crack - personally I'd bin it.

+1

I don't take chances with wheels/tyres - a failure at speed would not be good.

[StuB]

I had a cracked rear on my e60 and went for 4 new aftermarket wheels for less than 1 oem rear. Needed spigot rings fitted to sort vibration out though.