I am looking at getting some winter tyres for my mischief machine but I want to go for more rubber (higher profile) for better grip and pothole resistance (also cheaper).

This means I am swapping from 15 inch rims to 13 inch rims and I needed to calculate the correct tyres to fit.

After a bit of searching I found this calculator:-

http://www.tacomaworld.com/forum/tirecalc.php?tires=195-45r15-165-70r13

It seems the one of the clearest ones out there - I thought it might help you guys

Only fit tyre sizes listed in the cars handbook, anything else and insurance is likely to be an issue

A higher profile tyre will not necessarily give you more rubber contact, that would depend on the width, not the profile.

Wider tyres spread the car weight over a larger area, so reducing contact pressure. For ice and snow, narrower tyres will increase contact pressure, which is more beneficial. Look at the rally cars on ice and snow, they use quite narrow tyres. (No, you can't have the studs)

Going from 15s to 13s you might even find that the brakes no longer fit!

Proceed with (extreme) caution. The handbook may have some advice.

Yep - I am going narrow and tall for the snow - expecting lost this winter

I have my 195 45 R15 for Summer

ans now my 165 70 13 for winter (with snow tyres)

Thanks fingers - I forgot about the brakes

Also I need to get some offsets 20m,m I think - any ideas of a good source.

In the end I needed custom 40mm spacers but I found a place at the end of my road who were amazing. They are old school engineers who can make just about anything.

https://plus.google.com/107054205213730350888/about?gl=uk&hl=en

The guys name is Brian

Most Easterly Pandas said:

Only fit tyre sizes listed in the cars handbook, anything else and insurance is likely to be an issue

Click to expand...

Luckily I have a kit car...no manual to quote