Mixing tyres... well

[FussyFez]

I ordered 4 Yoko S.Drives from a well known internet tyre dealer yesterday, and ive just had a flick through their FAQ and found this;

*** said:

Should I mix Tyres?

Mixing tyres is not recommended, however you are able to mix and match if you wish as long as the tyre specifications match your existing tyres.

You should also be aware that we do not recommend fitting directional tyres to the rear unless you also have them on the front. You can however choose to fit directional tyres only to the front with non directional tyres fitted to the rear.

Could someone who knows please explain that last bit?

Thanks

[TonyRPH]

Seems to me they're saying that it's ok to have directional tyres at the front and non directional tyres at the rear, but not to mix them left to right - i.e. have a directional tyre on the front left, and a non directional tyre on the front right...? (and equally left rear / right rear)

[GravelBen]

Aren't there some high-end manufacturers who often specify directionals at the front and asymmetrics at the rear?

Edited by GravelBen on Wednesday 26th May 11:47

[jon-]

TonyRPH said:

Seems to me they're saying that it's ok to have directional tyres at the front and non directional tyres at the rear, but not to mix them left to right - i.e. have a directional tyre on the front left, and a non directional tyre on the front right...? (and equally left rear / right rear)

:yep:

GravelBen said:

Aren't there some high-end manufacturers who often specify directionals at the front and asymmetrics at the rear?

I believe you mean these:

[GravelBen]

jon- said:

I believe you mean these:

[img] http://www.tyrereviews.co.uk/images/tyres/pzero_co...

You may be right, I don't know the specific tyres in question but I've heard that both Porsche and Ferrari specify them that way on some models.

[Ozzie Osmond]

FussyFez said:

"You can however choose to fit directional tyres only to the front with non directional tyres fitted to the rear."

Could someone who knows please explain that last bit? Thanks

Brake balance.

Most braking is done by the front wheels. Cars have pressure limiting valves in the brake circuits to make sure the rear brakes are applied less than the fronts. If you mix tyres and put grippier ones on the back then you've got them on the wrong end!

[voicey]

GravelBen said:

Aren't there some high-end manufacturers who often specify directionals at the front and asymmetrics at the rear?

Yes - my 360 has Direzionale on the front and Asimmetrico on the rear.

[havoc]

voicey said:

GravelBen said:

Aren't there some high-end manufacturers who often specify directionals at the front and asymmetrics at the rear?

Yes - my 360 has Direzionale on the front and Asimmetrico on the rear.

As, by default, do a lot of 95-01 NSX's - there's hardly any choice now for the 16" fronts, so you end up with RE040 fronts and RE050A rears.

[Fatman2]

Ozzie Osmond said:

If you mix tyres and put grippier ones on the back then you've got them on the wrong end!

That's something I've always thought (and was conventional wisdom in my day) but recently I've heard the opposite is the correct way i.e. grippier tyres on the back and less grippier on the front.

To be honest I thought the fitter was giving me some BS as he couldn't be bothered to rotate my tyres for me but Michelin reckon the same.

I think the rationale is that most people know how to deal with understeer but haven't a clue about oversteer. Thus if you have grippier tyres on the back then oversteer is less likely to occur as the car will tend to understeer first.

I can see the logic but am not sure I totally agree. In my case I can't do anything about it anyway as my front/rear wheels are different sizes so invariably change when tread is low.

[jon-]

Fatman2 said:

Ozzie Osmond said:

If you mix tyres and put grippier ones on the back then you've got them on the wrong end!

That's something I've always thought (and was conventional wisdom in my day) but recently I've heard the opposite is the correct way i.e. grippier tyres on the back and less grippier on the front.

To be honest I thought the fitter was giving me some BS as he couldn't be bothered to rotate my tyres for me but Michelin reckon the same.

I think the rationale is that most people know how to deal with understeer but haven't a clue about oversteer. Thus if you have grippier tyres on the back then oversteer is less likely to occur as the car will tend to understeer first.

I can see the logic but am not sure I totally agree. In my case I can't do anything about it anyway as my front/rear wheels are different sizes so invariably change when tread is low.

I would much rather my mum / girlfriend experience progressive understeer than snap oversteer!

[OnTheOverrun]

Fatman2 said:

Ozzie Osmond said:

If you mix tyres and put grippier ones on the back then you've got them on the wrong end!

That's something I've always thought (and was conventional wisdom in my day) but recently I've heard the opposite is the correct way i.e. grippier tyres on the back and less grippier on the front.

To be honest I thought the fitter was giving me some BS as he couldn't be bothered to rotate my tyres for me but Michelin reckon the same.

I think the rationale is that most people know how to deal with understeer but haven't a clue about oversteer. Thus if you have grippier tyres on the back then oversteer is less likely to occur as the car will tend to understeer first.

I can see the logic but am not sure I totally agree. In my case I can't do anything about it anyway as my front/rear wheels are different sizes so invariably change when tread is low.

This depends on your definition of grippy though. Do we always assume deeper tread automatically means more grip? I know on many roads except on streaming water a well-scrubbed 4mm tyre will grip better than a brand new 8mm one. Howabout a motorway in heavy rain - I'd expect deep tread on the front and less deep on the rear to deal with aquaplaning better than vice versa. And lets not forget many manufacturers fit grippier tyres on the back and less grippy ones on the front from the factory - are they all wrong too?

[spikeyhead]

There's a significant difference in being able to handle power induced oversteer and a vehicle that has become fundamentally unstable through loss of rear grip.

[havoc]

spikeyhead said:

There's a significant difference in being able to handle power induced oversteer and a vehicle that has become fundamentally unstable through loss of rear grip.

But with fwd you keep your toe in and dial a handful of 'oppo' (sorry, couldn't resist!)...or with most fwd cars just unwinding a handful of lock is enough.

My 2p for most 'ordinary' cars - keep all 4 tyres the same make, keep them at 3mm or above, and it makes zero odds which is where...arguably you want more tread at the front as the rears follow in their tracks so need to do less water-displacing.

For performance cars - up to the owner, and their attitude towards handling.