Changing wheel size/speedo question (Again - Sorry!)

Hi, I asked a question a while ago about putting larger wheels on a car, and how it makes the speedo out. You guys were very helpful and I was given a calculator to work out the differance in speed ( http://www.polo-gt.co.uk/mechanical/tyrecalc.html )

But just to be a pain in the ass, I can't seem to find a near match in standard tyre sizes, eg: at the moment the car has 14" steels on it! ( 195/45/14 ) but if I want 16" or 17" wheels, I can't seem to find a standard size that would keep my speedo just under the speed, they all seem to be in excess of 8%, which I'm sure you'll agree is too much.
So my question is, does anyone know the 'standard' tyre sizes you can buy, or do you know how if garages can get speedos changed or do something to make it show the speed correctly? I'd go into a garage, but I can't afford new wheels at the moment anyway, so thought i'd ask some people who won't rip me off ;)

Thanks for any help

You can get the speedo re calibrated.

just adjust the width by 5mm each way - should apply < 5% to the amount

either that or you can normally get packages which replace a cirtain wheel/tyre setup.. just ask wherever you're buying the wheels from

I can see your problem, your already on low profile rubber on your standard wheels, so going to big wheels doesnt allow you to lower the profile sufficiently to keep the original rolling radius.

If you do want big wheels, your just gona have to get your speedo recalibrated. The larger rolling radius is going to make your acceleration slower in all gear, but your top speed in each hear higher.

I wouldnt go more than 2" bigger wheels than where on as standard as anything more will affect the handling considerably on 90% of cars.

Butuz

Ok, thanks for your help guys - interesting about the accel/top speed - didn't know that.

Was looking at 15 or 16" - seen some people with 19"'s on my car, how crazy is that!

Again, thanks all :)

Sean

No probs.

Btw - what car is it?

Butuz

Are your current 14" wheels 6/6.5" in width? Fine if they are, but otherwise a 195 section tyre is way too big! This might be throwing out your calculations, maybe your speedo is already out...

Thats a good point, do you know your speedo is correct in the first place? I know mine when I bought the car new, clock says I am doing 30mph gps certified show's that it was doing 26mph and it gets futher and futher out the faster I go. Thanks for the link though as I am changing from 15's to 17's

Aheam, I read the tyre size at night, with a led keyring - was abit off!

It's 165/65/14 ( should double check that again mind, was early this morning when I was de-icing the car I noticed.

Man I'm such a n00b with cars :D