Mixing RFTs & non RFTs

[Coyote]

Is there any problems with mixing RFTs with non RFTs.
Need to change the rears on Rachel's car but the fronts still have loads of tread depth left?

So plan to change the rears for non RFTs and leave the RFTs on the front until they eventually get changed for non RFTs as well.

cheers

 

[sars]

I have given this some thought after another poster here bought one from a dealer with mismatched front/rears and I cannot see any technical reason why you can't, just seems wrong to mix tyre types though and this would prevent me doing it.

Why not change all four and sell the fronts on eBay or here or buy a better make of RFT's than Bridgestones, there are plenty of threads on the subject, search using gannet in there as he swapped to another brand and rated them highly

 

[wegras]

Michelin PS2 RFT

 

[Coyote]

Michelin PS2 RFT

Yes but RFTs are twice the price of normal tyres.

Are you offereing to pay the difference in cost!

 

[cj10jeeper]

This one's been covered many times. Nothing illegal about it, but they 2 sets will perform differently on the limit and might just find you a ditch. If you were involved in an accident it could be cited as an issue.

For those reasons I'd not do it either and similar to Sars - change all 4 and sell the others on. After all it's a sports car not a family saloon

Some will tell you they have done it and had no issues.

Your call.

 

[Coyote]

This one's been covered many times. Nothing illegal about it, but they 2 sets will perform differently on the limit and might just find you a ditch. If you were involved in an accident it could be cited as an issue.

Well frankly if you are at those limits on the road you deserver o be in the ditch!

Now I fully understand that there will be a difference between a £20 tyres from a brand that you have never heard of but the difference between “quality” tyres should not be too much on the road.
The only difference I imagine is the two different sets will have slightly difference grip levels, but it is not as if we are putting super-soft SG 888s on two wheels.

The insurance issue is a valid point if it is the cause of the accident.

After all it's a sports car not a family saloon.

After all in real life a “sports car” can only be driven the same as most decent saloons unless you are on a track day and she has a real sports car for that.

It is her daily hack so most of the time it potters around on our over populated roads stuck at the back of a queue of traffic behind a 40mph Rover/Honda.

But all that said these are just your opinions and my opinions.

 

[cj10jeeper]

Coyote - apologies as I should have been clearer. When I say on the limit I mean under a stress situation such as an emergency stop, or having to brake on a corner due to an unforeseen problem. It's at those instants that the differences in the way the tyres perform ( how much grip at which instant) could be the issue. That's why in France you have to have the same brand on each axle and even in the uk cross ply can only be on one end of the car if mixed (can't recall which)

The reference to a saloon was that they are set up very differently. Often fwd, complaint, highly predictable, low powered, etc. as opposed tompowerful, light, rwd, etc. Much less chance of something exciting happening in a bog standard saloon

Of course at 40 mph and in slow moving traffic it probably doesn't matter one jot and to your point just our opinions, but you did ask

 

[PawnSacrifice]

I agree with sars, I don't actually think it would make that big a difference, and the driver aids on the car will equal out most things - the bigger issue for me would be them intervening and cutting the power if it thinks there's a difference in grip.

To be honest, on the UK roads these days you're very unlikely to get a surface that is going to give you similar enough of a surface to get equal grip all round anyway

This is all assuming that you are using similar spec of tyres, which if you are aware there might be an issue, you are going to do.

One thing, and this is more rhetorical, but surely even with matched tyres there is going to be a difference in performance, front to rear, on a car with a staggered setup? Especially bearing in mind the Z4 can have either staggered on non-staggered from the factory - right up to the 3.0, so surely the car can only be setup for one?

What do I do? Match all 4 tyres. If I buy a car where they aren't matched I'll get it sorted. But I think that has as much to do with OCD as anything else, well and wanting to use the car on track - where using the car on the very limit (I wish) and no driver aids, I think it pays.

Despite what I say, technically completely agree with CJ and, you did ask so you will get a lot of different views, even if people agree on the technicalities :wink:

One final thing, you should let your insurance company know if you are changing from run flats - didn't make a difference with mine, but had it noted just in case.

 

[Coyote]

Coyote - apologies as I should have been clearer. When I say on the limit I mean under a stress situation such as an emergency stop, or having to brake on a corner due to an unforeseen problem. It's at those instants that the differences in the way the tyres perform ( how much grip at which instant) could be the issue. That's why in France you have to have the same brand on each axle and even in the uk cross ply can only be on one end of the car if mixed (can't recall which)

The reference to a saloon was that they are set up very differently. Often fwd, complaint, highly predictable, low powered, etc. as opposed tompowerful, light, rwd, etc. Much less chance of something exciting happening in a bog standard saloon

Of course at 40 mph and in slow moving traffic it probably doesn't matter one jot and to your point just our opinions, but you did ask

I hope you did not take it that I was having a go at you; it is not meant at all.

I did not even think you could still buy crossplys. Not mixing them/radials is a real blast back in time. I remember taking a mk2 Cortina with crossplys for a test drive and every 20mph bend sounded like I was in the Sweeny there was so much screeching.

So in the end all you have to do is match all 4 tyres (same make & model) being irrelevant of RTFs or not. This is a pain as 3 of the tyres are nearly new with the other one down to the wear indicator. Hence it will have to be replaced with another RFT at a silly price or all 4 get changed to non RFT (long term preference as we don't see the point of RFTs) at more cost but less per tyre. I was just wondering how much difference there was to run 2 of each.
Whatever way we go it is going to cost lots of dosh.

For the record we inherited the tyre situation with the car so the last owner changed 3 of the tyres but not the 4th. :roll:

I understand the powerful light rwd thing as her other car has all those qualities (makes the Z4 seem like a barge)

 

[Finisterre]

try it and see.

 

[Coyote]

I agree with sars, I don't actually think it would make that big a difference, and the driver aids on the car will equal out most things - the bigger issue for me would be them intervening and cutting the power if it thinks there's a difference in grip.

To be honest, on the UK roads these days you're very unlikely to get a surface that is going to give you similar enough of a surface to get equal grip all round anyway .

In all the time I have driven cars with traction control both the Z4 and my 270bhp FWD estate, the only time it has ever come on it when pulling away from a junction and I do err ……….. drive in a spirited fashion.

This is all assuming that you are using similar spec of tyres, which if you are aware there might be an issue, you are going to do.

One thing, and this is more rhetorical, but surely even with matched tyres there is going to be a difference in performance, front to rear, on a car with a staggered setup? Especially bearing in mind the Z4 can have either staggered on non-staggered from the factory - right up to the 3.0, so surely the car can only be setup for one?

Looking at it all 4 tyres are the same size and it would be similar specs if we did it.

What do I do? Match all 4 tyres. If I buy a car where they aren't matched I'll get it sorted. But I think that has as much to do with OCD as anything else, well and wanting to use the car on track - where using the car on the very limit (I wish) and no driver aids, I think it pays.

Despite what I say, technically completely agree with CJ and, you did ask so you will get a lot of different views, even if people agree on the technicalities :wink:

I do have to match all the tyres as well but normally I can wait a while and do it as they wear. Would not want to take it on a track as there are far better cars for that (like Rachel's other car. :wink: )

As always with forums everyone has a different comment. Sometimes way too many and you end up even more confused.

 

[no fit state]

Speaking as someone who did mixed RFT with NRFT tires for over a year in rain, snow, ice and sunny days. I can say that I had no problems at all and would happily do it again

 

[Coyote]

Speaking as someone who did mixed RFT with NRFT tires for over a year in rain, snow, ice and sunny days. I can say that I had no problems at all and would happily do it again

Which way round did you have them?
Its a rear on ours that needs changing so would run the 2 NRFTs on the back.

 

[sp3ctre]

This one's been covered many times. Nothing illegal about it, but they 2 sets will perform differently on the limit and might just find you a ditch. If you were involved in an accident it could be cited as an issue.

For those reasons I'd not do it either and similar to Sars - change all 4 and sell the others on. After all it's a sports car not a family saloon

Some will tell you they have done it and had no issues.

Your call.

+1 for this... whatever your choose tyre-wise I do think wherever possible try to get similar solutions on each corner.... The Sars idea of changing 4 and selling the others on is a good one. I have to put my summer tyres on at some point soon and 2 of them are worn... I am probably going to stick 4 new ones on and either keep the other 2 good ones as spares or flog them on.

 

[Pilly]

I have non rfts on front and rfts on rear. Had this set up for about 2 months and have notice no real difference at all. I am about to swap rears over as have a nail in passenger rear which can't be repaired as its too close to sidewall. So personally I haven't had a problem.

On a side note I will have a drivers side RFT 5mm tread all over for sale if anyone wants it (sorry not trying to hijack this thread).

 

[no fit state]

Speaking as someone who did mixed RFT with NRFT tires for over a year in rain, snow, ice and sunny days. I can say that I had no problems at all and would happily do it again

Which way round did you have them?
Its a rear on ours that needs changing so would run the 2 NRFTs on the back.

NRFT on the back, RFT on the front. So the same as you are thinking of doing.

 

[AlanJ]

I think the point being made by CJ and others is that in normal driving conditions it will probably have no noticeable difference. It's when you need maximum grip and traction on all four corners in an emergency situation that the different tyre characteristics could catch a driver out. Of course the decision is a personal one but in the event of a serious road collision accident investigators will look at tyres across the axles - a qualified technical examiner will be able to establish if different tyre characteristics may have been a contributory factor to an incident.

A bit like wearing a wellington boot on one foot and a slipper on the other. No problem until it rains......

 

[Coyote]

I think the point being made by CJ and others is that in normal driving conditions it will probably have no noticeable difference. It's when you need maximum grip and traction on all four corners in an emergency situation that the different tyre characteristics could catch a driver out. Of course the decision is a personal one but in the event of a serious road collision accident investigators will look at tyres across the axles - a qualified technical examiner will be able to establish if different tyre characteristics may have been a contributory factor to an incident.

You can apply that logic every time you replace a tyre you have to replace all four, as a tyre a year newer than the rest will have a different grip level even though they are all the same make/type.
As i have no knowledge/experience of them, why will RFTs have different grip levels to other tyres?
All I know is they make the roads near us feel like you are on an African rally.

A bit like wearing a wellington boot on one foot and a slipper on the other. No problem until it rains......

Are run flats really that bad then, like slippers in the rain? Or do you think we are putting slicks on the back?

I was under the impression it was more a stituation of wearing a Wellington boot on one foot and a wellington boot with a steel toecap on the other.

 

[Finisterre]

just guessing here but I imagine the causes of an accident will be very loosely coupled to how the axles are shod

what are the choices
oversteer
understeer
not stopping quickly enough
losing the back end and typically spinning off or shooting straight into a hedgerow.

they all look (to me) avoidable,
foolish driving is going to be the problem, not the tyres.