Mixing RFTs with non-RFTs

D

djstan

Active member
 Bristol
Thought I would pop a post up as I have been needing new tyres for a while - over the winter the car has been feeling more and more uncomfortable riding on the (worn) RFTs, so I was strongly considering buying non-RFTs for the car. Thing is, the front tyres still had plenty of tread left, so it felt like a waste to replace them, so the solution I came up with was to replace the rears with non-RFTs and keep the RFT fronts.

I asked on here and the general advice was (to paraphrase) "not on your life, pal - the car will be a deathtrap".

I also Googled other sites like Pistonheads and while there were a lot of similar comments, there were also some reports of people running BMW 335i, M135i etc. with a similar setup without issue, so I decided "to hell with it"/to be the z4-forum guinea pig and ordered the non-RFT rears (fully expecting, I might add, to have to hot foot it a couple of days later to get the fronts done before I killed myself!).

And the results have been..... not a lot. The car feels just as planted (if not more so, actually), just as sticky, just as happy to grip in corners - in fact there has been very little fuss at all.

The difference in ride quality and volume is really noticeable though - when going over bumps and things, the front of the car will 'crash', while the rear of the car will just politely 'thump' (if that makes sense). The rear of the car is so much quieter now too. A couple of interior rattles have now stopped too, interestingly.

I'm expecting to run this setup until the rears need replacing again, at which point I imagine the fronts will need doing too, so will change them all for non-RFT, but I thought I would offer you all my findings so far :) :thumbsup: :driving:
 
You will be fine :thumbsup:
I had the same issue with my old 335d. Fitted non rft's to rear of the car & ran rft's on the front with no problems what's so ever ! People will tell you to change all 4,that's fine if you can afford it. Or sell the fronts,but you will get buttons for them. I drove the car hard at times & never had a problem. Must have done 12/15k miles with that set up until my fronts were scrubbed. :thumbsup:
 
Do you have a BMW warrantee and, if so, did you investigate if non-RFTs invalidate the warrantee?
I'd shift from RFTs tomorrow if it didn't affect my warrantee. Consensus seems to be it does though. I guess I should just ask the dealer!
 
Only way to tell what's actually going on when you change something is DSC/TC completely off. Until then what you're feeling is well the DSC can correct the car not how good the tyres are. Anyway if you're going to change one axel to RFT tyres it should be the rear as that'll rear bias the grip which promotes a little more understeer.

35isDreamer said:
Do you have a BMW warrantee and, if so, did you investigate if non-RFTs invalidate the warrantee?
I'd shift from RFTs tomorrow if it didn't affect my warrantee. Consensus seems to be it does though. I guess I should just ask the dealer!
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Legally BMW UK have to provide evidence that the change cause the damage. The thing is though you're going to have to force the issue, potentially in court.
 
If you have a Bmw warranty & worried about that,keep the rears with a couple of mm left & put them on if you have warranty claim :thumbsup:
I'am going to change my rft's soon on my 35is,will keep the rft's if it needs a warranty claim or I sell the car. :D
 
It is annoying that BMW UK try to wriggle out of warranty work due to changes which actually *reduce* the stress put on components.

RE: keeping OE RFT tyres for warranty work note that the mileage, tyre manufacture date and wear may not match up. Which may put you in hotter water of trying to hide modifications after the fact.
 
The characteristics of handling, tyre wear may be fine in a mix and match for 90% of the time and in normal road conditions.

However it is when the conditions change - rain, wet roads, ice, snow etc and road surface construction (tarmac, Shellgrip, bonded granite stone chip)- that the individual characteristics of a tyre will make a difference. This may not be immediately noticeable but may become apparent in extreme circumstances - emergency braking, traction loss causing a skid for example. Of course we all try to drive to avoid any emergency response situations but they do happen.

It a bit like wearing a leather soled shoe on one foot and a rubber soled shoe on the other. Fine most of the time but water characteristics will significantly change as ambient conditions change.

Its certainly a matter of choice but if a situation arises which looks like an insurance clim (and particularly where serious injury is involved) any subsequent vehicle examination will look a tyre condition and mix across axles. As we know (and often commented on the Forum) insurers will seek any opportunity to reduce liability in the event of a claim.

The choice of tyre and mix across axles is individual but for me the choice is obvious - the only point of contact I and my Zed have with the road is through the tyres so I choose the best I can afford suited to the vehicle and unlike wearing 'odd shoes' the same across all axles.
 
This feeds in to what I was saying about the DSC. Because it's so good at correcting the car you don't notice the differences until things are getting quite bad. I drive a lot with DSC off on my 1er. It's amazing that on a road with small surface undulations that I can go down without any steering correction with DSC on & no lights flashing on the dash. With DSC off I'm having to make so many corrections that it stars feels dangerous at 3/4 the speed. Same sort of things with tyres it'll dial out a lot of the difference between tyres.

Best thing is same make/model of tyre on all 4 corners, ideally you want to keep it to non-XL or XL on both sets as well but this is less important than RFT/non-RFT.
 
I bought my E89 as an AUC at the beginning of last year and it was only when I took it for a service just before xmas that they told me I had RFT/front and non/RFT rear.
Obviously the previous owner changed them, but the dealer where I bought it 'strangely' never mentioned it.
I've never had any issues though and the car drives great, I was planning to swap out the RFT's anyway when the time comes so wasn't too bothered.
 
Z4midable said:
I bought my E89 as an AUC at the beginning of last year and it was only when I took it for a service just before xmas that they told me I had RFT/front and non/RFT rear.
Obviously the previous owner changed them, but the dealer where I bought it 'strangely' never mentioned it.
I've never had any issues though and the car drives great, I was planning to swap out the RFT's anyway when the time comes so wasn't too bothered.
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Dealers never mention anything about the tyres unless you explicitly ask. Before I bought my current car, I was looking at a number of other AUC E89 and E92s. I was almost set on one car until I asked about the tyres... Khumo in the rear and Hankook in the reat. Then I found another great example... until I found out it had Sunny tyres. Clear signs of people hating their cars...
 
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