Any issue mixing tyres across front and rear axles?

[christoferlloyd]

Hi Everyone.

I bought a 325ti Sport last month and am coming up to changing all four tyres - three are quite worn and one has c. 2k on it (will keep as spare).

The car has staggered tyres (225/45/17 front, 245/40/17 rear) and am planning to put Goodyear F1 Asymmetric 2s on the front and Dunlop Sport Maxx RTs on the back axle. I know it's not wise to mix tyres across the same axle, but is there any reason why you shouldn't have different tyres on front and rear?

Am also planning to get a full Hunter alignment done as the tracking is the one thing that seems a little bit off with the car, so hopefully new tyres and alignment will get it driving perfectly...

Many thanks,

Chris

[TheEnd]

No issues that way.
As it currently is, there's going to be differences in the characteristics down to the width, and no one has died just yet.

[BritishRacinGrin]

BMWs can be a bit fussy with this kind of thing. Personally I wouldn't, just in case of the one in twenty chance that this particular combination brings on unpleasant tramlining / rear steer characteristics.

[Leins]

I had a nightmare with the handling on my 325ti Sport (optional 18" MV2s) with mixed tyres (old Bridgestone Potenzas front / new Dunlop SP9000s rear). Swapping the fronts to new SP9000s immediately resolved it

Have seen plenty of posters on here in the past claiming it's not a problem, but that just means they've not experienced it themselves

Edited by Leins on Monday 21st April 18:31

[anonymous-user]

Leins said:

I had a nightmare with the handling on my 325ti Sport (optional 18" MV2s) with mixed tyres (old Bridgestone Potenzas front / new Dunlop SP9000s rear). Swapping the fronts to new SP9000s immediately resolved it

Have seen plenty of posters on here in the past claiming it's not a problem, but that just means they've not experienced it themselves

Edited by anonymous-user on Monday 21st April 18:31

Likely to be more to do with old/new than makes of tyre, but I do wonder why the OP wouldn't put the same brand on all four, given that all four are being changed?

[helix402]

I would advise matching tyres all round. I drive a 328i, it drove poorly with different make tyres on front and rear.

Currently on Goodyears all round, same size as OPs.

[Leins]

REALIST123 said:

Likely to be more to do with old/new than makes of tyre, but I do wonder why the OP wouldn't put the same brand on all four, given that all four are being changed?

I did wonder this at the time (2006), but when I then replaced the SP9000s on the back again a year or so later the handling remained perfect. I had even thought the issue was caused by something else, and a broken spring was found when I brought it into BMW to investigate, but this turned out to just be coincidental. Eventually, after a few weeks of horrid handling, I found a thread on a US site about someone else who had suffered from the same issue with (different) mixed tyres on a 330ci Sport. They replaced the fronts with new matching tyres to resolve it, so I did the same and was back in business

However, I've a sneaky suspicion that it may only be certain combinations of tyres, on certain suspension/wheel diameter, and with certain wear rates. Hence why it's possibly a rare occurrence, but I'd never chance it again

[christoferlloyd]

BritishRacinGrin said:

BMWs can be a bit fussy with this kind of thing. Personally I wouldn't, just in case of the one in twenty chance that this particular combination brings on unpleasant tramlining / rear steer characteristics.

Hmm. I had heard this kind of thing, so maybe it's best to stick to one tyre for both ends...especially as tramlining is one of the things I'm looking to fix...Thanks.

[christoferlloyd]

REALIST123 said:

Likely to be more to do with old/new than makes of tyre, but I do wonder why the OP wouldn't put the same brand on all four, given that all four are being changed?

Goodyears get slightly better reviews, but Dunlops are significantly lighter. Just wondered if there was any wisdom in putting heavier tyres on the front axle (thought they might add a bit of weight to the light steering) and lighter tyres on the driven axle to reduce rotational mass - grip levels should be similar so wouldn't expect any handling change. Can't imagine any difference would be that noticeable though...

[anonymous-user]

christoferlloyd said:

REALIST123 said:

Likely to be more to do with old/new than makes of tyre, but I do wonder why the OP wouldn't put the same brand on all four, given that all four are being changed?

Goodyears get slightly better reviews, but Dunlops are significantly lighter. Just wondered if there was any wisdom in putting heavier tyres on the front axle (thought they might add a bit of weight to the light steering) and lighter tyres on the driven axle to reduce rotational mass - grip levels should be similar so wouldn't expect any handling change. Can't imagine any difference would be that noticeable though...

Though there will be some driving gods on here who will insist they would notice the lower unsprung weight, no one in truth would, especially compared with the outgoing old tyre set.

[msej449]

Having worked for Pirelli, I would recommend that you don't mix tyre types. This isn't just a manufacturer's scam - they only test with their own tyres, obviously. This is especially the case if a manufacturer has directional and asymmetric designs. It might be OK but it's unlikely to be a tested combination.

[rm163603]

I had an e46 330i touring a few years back and suffered with the instability mentioned when I swapped the back tyres to a different brand to the front.

It was truly horrible... On m/ways the DSC would trigger at high speed going around gentle curves.... It was pretty buttock clenching.... I swapped the fronts as well and it was all sorted immediately.

[Leins]

^^^ Yep, that's exactly what I experienced too, thought it wanted to punt me off the road when exiting motorways. Many who haven't seem to think it's just a bit of tramlining

Don't suppose you remember the tyre brands you hit the problem with?

[rm163603]

Leins said:

^^^ Yep, that's exactly what I experienced too, thought it wanted to punt me off the road when exiting motorways. Many who haven't seem to think it's just a bit of tramlining

Don't suppose you remember the tyre brands you hit the problem with?

I do indeed.

This is going back a few years now so tyre models may not be the same now...

I had Michelin PS2s on the front and Pirelli P Zero on the back.

The rears wore out so I swapped them with Goodyear Eagle F1s (the old version not the current ones).

I had the same diagnosis of a broken spring but replacement made no difference.

4 wheel alignment made no difference.

The only thing that sorted it was swapping to Eagle F1s all round (new fronts).

It was really horrible, not just a bit of tramlining (which the car did at the best of times).

As I say you would feel a horrible yawing sensation on turn in followed by DSC intervention and much palm sweat!

This is at no more than 70mph.

I remember my drive to work at the time took me from Guuildford to Weybridge on the A3. Coming home the long sweeping left on the A3 southbound by the Burpham exit would be a white knuckle ride.

[Leins]

^^^ Aha, interesting, thanks!

I remember trying to follow a boggo Fiesta exiting a roundabout over the M56 and having to leave them off. Not exactly the "ultimate driving machine" that day. Never been so happy as when I swapped to matching fronts and instantly had my car back!

[gizlaroc]

I had the springs, struts, bushes, wishbones and all sorts changed on my M3 under warranty as it was a twitchy mess.
Then after nearly giving up on it got a call from BMW who said they had a tech in from another branch who races M3s, bring the car down so he can see it.
He took it down the road and after the second bend said 'You have mismatched tyres front and rear!'
I insisted they were PS2s all round, but sure enough when we looked the fronts were PS1s.
We went back, put PS2s on the front and BINGO!!!
Car was nice and planted again.


Not saying al tyres do this, but be prepared to change the others if it does start to feel funny.

Don't mix a symmetrical tread with an asymmetrical tread he said, that will be weird 9 times out of 10.

[rm163603]

The only thing I'm wondering is whether the compact will be as sensitive as the other e46 models....

The rear suspension is different so may not be as much of an issue....

[gizlaroc]

rm163603 said:

The only thing I'm wondering is whether the compact will be as sensitive as the other e46 models....

The rear suspension is different so may not be as much of an issue....

Since then I have had a 320d on mixed tyres for a few days and that was very skittish, a Z3 which again was lethal and a 335i that was fine.

It is the RWD and traction system that does it I think.

[Leins]

rm163603 said:

The only thing I'm wondering is whether the compact will be as sensitive as the other e46 models....

The rear suspension is different so may not be as much of an issue....

It can be, mine was a 325ti

[rm163603]

Leins said:

It can be, mine was a 325ti

Ah OK...

You wonder if its a quirk of the dsc system? It almost seemed to trigger causing the instability...