MPSS Cup 2s At last..

[007 VXR]

275 35 19 = £284
245 35 19 = £234

[Granby]

007 VXR said:

275 35 19 = £284
245 35 19 = £234

I know someone who would be happy to bed them in for you

[lee st]

I paid 588 for 4 mpss
Fit m135i wheels. It'll save you a fortune

[007 VXR]

lee st said:

I paid 588 for 4 mpss
Fit m135i wheels. It'll save you a fortune

but not cup 2s

[007 VXR]

Granby said:

I know someone who would be happy to bed them in for you

[neiljohnson]

You going back to 275's?

[007 VXR]

neiljohnson said:

You going back to 275's?

They only just started doing 275s only other sizes are 265 or 305.
realy want to try these tyres, so will have to be 275s as soon as i have the spare cash

[Xpuffin]

If the compounds good then the width difference won't matter.
Mark, I find myself with plenty of free time, will pop down one day next week.

[007 VXR]

Xpuffin said:

If the compounds good then the width difference won't matter.
Mark, I find myself with plenty of free time, will pop down one day next week.

[EmmaJ]

Surely a cup tyre needs much more heat built up to get to it's optimal working temperature so for the most part would be compromised for everything other than a serious noon?

Or am I missing something?

[ARAF]

Xpuffin said:

If the compounds good then the width difference won't matter.

I went through this with motorcycle tyres. When the width is greater, the contact patch is larger, but as the mass acting on the tyre is constant, the pressure on the tarmac per square inch is less, which affects the friction between tyre and tarmac. I didn't try any fancy maths, but decided that a wider tyre will aquaplane easier.

At about 4% difference in width (275 v 285) I don't think it will be noticeable.

[SturdyHSV]

ARAF said:

When the width is greater, the contact patch is larger

Not quite!

Can't believe I'm thinking of correcting ARAF, but here goes.

When the tyre is wider, the contact patch is a different shape, but it isn't larger.

Why? The contact patch is dictated by the pressure in your tyres.

34psi say? So there'll be 34 pounds per square inch.

So say the car weighed 3400 pounds, there's going to be 100square inches of contact patch, whether you like it or not.

I assume wider tyres aquaplane easier because you're making the contact patch very wide but very short in the direction of travel

[ARAF]

SturdyHSV said:

ARAF said:

When the width is greater, the contact patch is larger

Not quite!

Can't believe I'm thinking of correcting ARAF, but here goes.

When the tyre is wider, the contact patch is a different shape, but it isn't larger.

Why? The contact patch is dictated by the pressure in your tyres.

34psi say? So there'll be 34 pounds per square inch.

So say the car weighed 3400 pounds, there's going to be 100square inches of contact patch, whether you like it or not.

I assume wider tyres aquaplane easier because you're making the contact patch very wide but very short in the direction of travel

Plenty have done it before, and you're quite right. In my defence, we were playing with pressures as well and I've omitted that.

[007 VXR]

ARAF said:

Plenty have done it before, and you're quite right. In my defence, we were playing with pressures as well and I've omitted that.

begs the question,
what is the best psi for a 285 tyre, with best grip being the goal?

[SturdyHSV]

007 VXR said:

begs the question,
what is the best psi for a 285 tyre, with best grip being the goal?

For straight line traction? Something lower.

For cornering grip? Something higher.

For all round? Whatever Michelin recommend I'd assume

Although this isn't the answer you're after, unfortunately, the real answer is "It's really complicated" hence why listening to Michelin is probably your best bet

[007 VXR]

SturdyHSV said:

For straight line traction? Something lower.

For cornering grip? Something higher.

For all round? Whatever Michelin recommend I'd assume

i run 35 front
33 rear.

[ARAF]

007 VXR said:

ARAF said:

Plenty have done it before, and you're quite right. In my defence, we were playing with pressures as well and I've omitted that.

begs the question,
what is the best psi for a 285 tyre, with best grip being the goal?

Absolutely no idea.

We were looking at smaller contact areas being better in the wet, as less chance of aquaplaning, so using higher pressures - but then the tyres were going cold as the rubber wasn't flexing as much, and therefore not gripping as well.

Everything you do will be a trade-off.

[Tattooboy]

35/19's are soooo yesterday, how much for 30/20's

[007 VXR]

Tattooboy said:

35/19's are soooo yesterday, how much for 30/20's

only £230 for 285s ..

or £180 for vredestins (if your scotish)

[stigmundfreud]

Granby said:

007 VXR said:

275 35 19 = £284
245 35 19 = £234

I know someone who would be happy to bed them in for you

With, or without, traction control?