Runflats front Non Runflats rear?

[Smartbear]

For much of the time as many say won’t notice much difference - they’re both a round bit of rubber.

It’s the 5% when all hell breaks loose - Personally, I spend money on the same high quality tyres for the point RW mentions, they’re dynamically different & in an emergency won’t be consistent.

It’s a personal preference, where knowing you’re relying on only 4 small bits of rubber the size of your hand I want this area to perform as best as physically possible in those extreme emergency stress situations.

I suppose it also comes down to the view an insurer would take were you to be involved in an accident.

My car passed an MOT with that set up, so it was road legal
Rob

im not sure tyre spec is part of an mot above tread depth and damaged sidewalls

If you presented an illegal mix such as cross ply & radials on the same axle they would fail the car.
I don’t think it’s illegal to run runflats & non rf tyres front/rear
Rob

[Jembo]

Maybe a question for our resident Mr. Flux

[Busterboo]

... I don’t think it’s illegal to run runflats & non rf tyres front/rear
Rob

But not ideal, Rob. So why compromise?

[vld]

I don't change tires on an axle unless they are worn out. I currently run with RF on front and NRF on back. Still more comfort and no difference in handling. I drive fast (up to 200km/h where legal), I break short and corner aggressively. In my opinion, the only difference there is is about how they handle a puncture, nothing more.

[Pbondar]

Various statements from tyre suppliers...and manufacturers...I think I know which side the insurance companies would go with in a big fatal...your personal opinion or the suppliers ...

‘You’ll have safer handling and prevent damage to other parts of your car when all four tires on your vehicle match closely in type, tread depth and size. This is not the case when you mix and match run-flat tires with standard tires. Here’s why.

Run-flat tires (RFTs) are built with reinforced sidewalls, which make them a lot stiffer. This is why they can be driven between 50 and 100 miles (depending on the type) at about 50 mph with low or no air.

Difference between a run-flat and standard tire.

When there’s a big difference between your front and rear tires’ sidewall flex, your car’s handling will be imbalanced. You won’t have proper stability, especially when you need it most: around corners, at highway speeds and when swerving.

Due to the way they’re made, RFTs typically wear out long before standard tires. If you mix and match, you may end up with significant differences in tire tread depth between your front and rear axles. This could result in other problems if you replace only the two worn-out tires.’


‘Mixing Conventional Tyres with Run Flat Tyres

As a general rule of thumb, you should avoid mixing different tyre types on a vehicle. This is also true of combining conventional and run flat tyres on a car – as their handling characteristics may differ, they should not be mixed on a vehicle.’


‘Can I Mix Tires?

As a general rule, tires should not be mixed on any vehicle unless specified as acceptable by the tire or vehicle manufacturer. Drivers should avoid mixing tires with different tread patterns, internal constructions or sizes (unless front and rear staggered sizes are specified by the vehicle manufacture), and use identical tires on all of their vehicle's wheel positions in order to maintain the best control and stability. Additionally, drivers should never mix winter tires with all-season/summer tires, or mix run-flat tires with non-run-flat tires.’

[john-e89]

Various statements from tyre suppliers...and manufacturers...I think I know which side the insurance companies would go with in a big fatal...your personal opinion or the suppliers ...

‘You’ll have safer handling and prevent damage to other parts of your car when all four tires on your vehicle match closely in type, tread depth and size. This is not the case when you mix and match run-flat tires with standard tires. Here’s why.

Run-flat tires (RFTs) are built with reinforced sidewalls, which make them a lot stiffer. This is why they can be driven between 50 and 100 miles (depending on the type) at about 50 mph with low or no air.

Difference between a run-flat and standard tire.

When there’s a big difference between your front and rear tires’ sidewall flex, your car’s handling will be imbalanced. You won’t have proper stability, especially when you need it most: around corners, at highway speeds and when swerving.

Due to the way they’re made, RFTs typically wear out long before standard tires. If you mix and match, you may end up with significant differences in tire tread depth between your front and rear axles. This could result in other problems if you replace only the two worn-out tires.’


‘Mixing Conventional Tyres with Run Flat Tyres

As a general rule of thumb, you should avoid mixing different tyre types on a vehicle. This is also true of combining conventional and run flat tyres on a car – as their handling characteristics may differ, they should not be mixed on a vehicle.’


‘Can I Mix Tires?

As a general rule, tires should not be mixed on any vehicle unless specified as acceptable by the tire or vehicle manufacturer. Drivers should avoid mixing tires with different tread patterns, internal constructions or sizes (unless front and rear staggered sizes are specified by the vehicle manufacture), and use identical tires on all of their vehicle's wheel positions in order to maintain the best control and stability. Additionally, drivers should never mix winter tires with all-season/summer tires, or mix run-flat tires with non-run-flat tires.’

I totally agree on the insurance issue, however I’d suggest, strongly, the tyre manufacturers are just covering their backs due to the Sue culture blighting the civilised world.

It’d be worth speaking to your insurer to see what they say, although they’ll errr on the side of caution so we know how that’ll go so yes, on that score don’t mix and match.

[Smartbear]

... I don’t think it’s illegal to run runflats & non rf tyres front/rear
Rob

But not ideal, Rob. So why compromise?

It was only a temporary thing, those wheels & tyres are long gone now
Rob

[Busterboo]

... I don’t think it’s illegal to run runflats & non rf tyres front/rear
Rob

But not ideal, Rob. So why compromise?

It was only a temporary thing, those wheels & tyres are long gone now
Rob

I'd forgotten you ever had 'em, if, indeed, I ever knew.

[MKZ4000]

Would it be ok to use a Runflat as a spare tyre when the fitted tyres are non runflats.

Are spacesavers fitted with normal tyres or runflats?

[Lazza]

If you are planning to mix runflat and non runflat across an axle I’d treat it like a space saver and keep the speed below 50mph and only as far as is necessary.

[flybobbie]

I was having about two punctures year with non RFTs.
Then i bought 4 years ago and keep a space saver in the boot.
Now only had one slow puncture since in a near worn out tyre, that was slow and i kept pumped up until i was in a position to replace it..
I tried mixed RFT and non RFTs, the car drove like a pig.

[Lazza]

I was having about two punctures year with non RFTs.
Then i bought 4 years ago and keep a space saver in the boot.

Where do you drive??? I think I’ve only had 4 or 5 punctures in over 30 years if driving!!!

[flybobbie]

On the exit to where i work was a kitchen fitter, his skip was on the opposite side of the road. I think he may have dropped a few screws.

[Pbondar]

In the 1970s quite a lot of research went into motorcycle stability as policeman were being spat off their BMW bikes..it was found that the situation was created by compound variables and a relatively minor change in one could result in a previously stable bike going highly unstable..

I thought the main issue was that the BMWs they used were not designed to carry the weight that the police strapped onto it and the bikes were unstable at speed. They were basically top heavy and the weight was in the wrong places. They were then limited to what speed they were allowed to do until they fixed the problem.

Thats what i said..the issue was that in certain cases only a minor additional change caused instability where previously there wasn't at that speed..

[belljul]

So my rear RF were close to replacing, so I did, with NRF (attracted to the promise of lower noise and smoother ride) so got some Michelin Cross Climates in prep for the sub 7'c we get in Scotland. I left the RF on the front axle (6-7mm).
I have Cross Climates on my wife's car (F&R) and leave them on all year round.
I was overtaking in the Zed along a long straight country road, and the front end was jumping all over the place as it hit the lumps and bumps in the road. I was seriously afraid.
Needless to say I have ordered a set of Michelin Cross Climates for the front axles for next week. Fingers crossed I will not be bounced off the road next time I overtake!