different size tyres.

coupe

Torque Master
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62
Location
woking, surrey
Car
toyota mr2 mk1.
anyone know what the regs are on having different size tyres on the front compared to the rear.

just thinking about going for a funny car look.:blink1:
smallish front tyres and largish rears.

just playing with ideas at the mo.
 
there is none as long as you have the same size on the same axle your ok

so you have have 22's on ethe rear and 10's one the front
 
thats good.

so i have 205/70's on the rear at the mo.
that means i could fit 195/65's on the front.
give me the slight nose down look i'm after.
kool.
 
You do need to comply with the car's original specified range of fitments in general. It's important to make sure that your insurance underwriter is aware of any changes you make.

If your car is designed to have the same rolling radius front and rear then you have to be aware that ABS and other dynamic systems may behave unpredictably unless you subsequently program the systems to cope with the different angular wheel velocities.

Wider tyres are often used at the rear of ultra high powered (by which I mean +500bhp) RWD cars simply to reduce the risk of violent oversteer. It's possible for a car such equipped to exhibit savage understeer as the rear tyres are forcing the car forward at such a high rate.

Understeer is usually more easily controlled than oversteer, where over-reaction by the driver can create a fishtail effect. This often results in a complete loss of control. So can snapping the accelerator shut do something similar. All the momentum piles onto the front wheels, the rears lose traction and round ya go!
 
Extra width at the rear will improve traction in a straight line - especially from a standing start.

Check the vehicle owner's handbook for approved fitments.

But please to clear it with your insurer if you're deviating from a standard f/r combination. Most will accept this without any concern but it's best to ensure that you're not putting your legal position (with your insurer) in jeopardy.

You also don't want a jacked up rear suspension with a lowered front suspension.

This will not benefit handling and grip at all. It's likely to upset the geometry and leave you with a car that has strange toe-in/toe-out problems (IBM garnered this phrase in the 1990s) 'unpredictable results'.

You'd be better fitting some untra high quality rubber all round in my opinion. Pirelli P7 is a suitable fitment for your car.
 
Extra width at the rear will improve traction in a straight line - especially from a standing start.

Only if you get better tyres than what you had before...wider tyres dont give you a larger contact patch, the only things that determine that are the weight acting on the tyre and the pressure inside it.

The only thing to look out for is if you have a 4x4, different rolling radius front to rear can totally ruin the diff
 
What does happen with a wider tyre is that whilst the contact patch area is approximately the same as a narrower tyre (as pointed out by Munday), it is wider and shorter. This means that the percentage of the tyre's circumference that is in contact with the road at any one time is less so the tyre has more time to cool down. This means that softer compounds can be used, increasing the tyres ability to grip the road/track surface.
 
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What does happen with a wider tyre is that whilst the contact patch area is approximately the same as a narrower tyre (as pointed out by Munday), it is wider and shorter. This means that the percentage of the tyre's circumference that is in contact with the road at any one time is less so the tyre has more time to cool down. This means that softer compounds can be used, increasing the tyres ability to grip the road/track surface.

Exactly :)
 
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Yes, but it is different for each application.

That's kind of where I was going. No point in having 245/40/18 fitted to a Corsa as there's likely to be insufficient pressure (force/unit area) to make for good lateral grip.

I suppose it also depends upon intended usage - ie. forest rally stage different to track different to general road setup etc.
 
A lot of car makers are starting to use larger width tyres on the rear (or narrower in the case of the Audi RS3). As Luton says, providing they are on the same axle you should be fine.
 
:lol: I never tell people off for resurrecting old threads and in fact I encourage it! ;) We get new members all the time and things often change or get updated so it keeps things topical and fresh and I'd rather see a long thread than lots of very similar short threads.
 
Space savers to be used at lower speeds for only to get you safely to the nearest tyre shop, not for normal or extended driving. Not that they can prove you've been using it otherwise but any way...
 

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