Technical HELP! My new tyres are the wrong size!

[Voucher Boy]

Hi Guys, hoping that you are able to help me out regarding the tyres I need for my classic 500. I have bought some Cromodora rims and wanted something a little wider for them. The previous tyres were 135/80/12 and were a little narrow, so I ordered some 145/80/12 tyres from Blackcircles. I fitted them onto the rims and then went to fit them on the car, but they are massive and even foul the body on the front. The problem is not the width, but the diameter. They are much larger diameter for some reason. I knew that because the '80' is a ratio, it would mean that the overall diameter would increase very slightly going from 135 to 145, but these are ridiculous! See attached images. Can anyone suggest what tyres I need (would prefer slightly wider), and why these new ones are so big? What did I do wrong?

 

[bugsymike]

Have you checked on one of the tyre specialists online that you enter your tyre size and compare the rolling circumference etc. with the tyres of your choice, they also say how it will affect your overal gearing/speed etc.
Apart from that as you have only gone up one size , is it possible your suspension has sagged, I know it has happened to me.

 

[smart51]

the 80 of the 135/80 R12 is the tyres nominal height as a percentage of its width. A 145/80 tyre is going to be taller than a 135/80 tyre.

 

[ZaphodB]

Have you checked on one of the tyre specialists online that you enter your tyre size and compare the rolling circumference etc. with the tyres of your choice, they also say how it will affect your overal gearing/speed etc.

Yeah there's loads of calculator or comparison website pages

This for instance:

Tire Size Calculator

The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.

tiresize.com

Click the comparison tab and enter your numbers.
As smart51 indicates it's not a difficult calculation anyway