TangoVTEC

Go from a 45 profile to a 40 but keeping oem widths?

sound_wave

The profile is the height of the tyre, isn't it? If it is, the radius of the tyre will drop, so you're speedometer won't be accurate (unless the speedo compensates automatically).

I think that's why the 17" wheel's tyrewall is an inch narrower than the 16" one.

GavB

Assume you mean for the fronts? In which case speedo is not a problem, but it could look bad! Will make your wheels look smaller and your arch gap bigger. Why do you want to do it?

sound_wave

I agree with Gav - mis-matching tyres would look garbage. I assume it's just becasue you can get cheaper tyres, right?

TangoVTEC

The vredesteins I want only come with a 40 profile, Also the reduced sidewall might let me drop it a little/stop it rubbing.

veehexx

http://www.club80-90syncro.co.uk/Syn...calculator.htm

TangoVTEC

I did want to get Ultrac Sessantas all round, but they are out of stock of the OEM front size.

Guess a 225 is out of the question too.

No matter, ill find summit else.

Thanks all.

veehexx

if it's as simple as 3 is twice as soft as 1.5, then yes. 5% profile change does cost.
ofcourse it might help on steering feel; stiffen up the somewhat soft front end (my goodyear eagle f1's are a touch soft)

speedo out shouldnt make a difference as the speed is taken from the gearbox and thus the rear wheels speed, and not from the front wheels. if you were changing the rolling radius of the driven wheels, then that'd be different. front wheels will just 'keep up' and will have a higher RPM as minor as it is.

your also saving a bit of unsprung mass too, so that'd help aswell

GavB

I have 225/45 on mine for more front grip. 225/40 would probably be asking a bit much of the sidewalls though.

Benjamico

I've just ordered 245/35/17 for the rears as I wanted to reduce side wall wobble, I'll report back how I get on...