Mercedes AMG Alloy Tyres

[sidmon]

I've got a set of Mercedes AMG alloys with 265/35/18 rear tyres. Would I be able to stick 265/40/18 tyres on the rear instead, without causing any trouble??!!

 

[bigasotonuk]

Hi,
What car is it?

 

[sidmon]

'96 E420 W210 Estate

 

[rf065]

It would alter the gearing and speedo readings by over 4%.

Changeing to 265/40x17 would keep everything the same or 245/40x18 would only be a difference of 1.6%.

Why do want to change anyway?

Russ

 

[sidmon]

I've been offered a pair for a very good price. Why would 245/40/18 affect by only 1.6% and mine would be 4%?

 

[rf065]

I've been offered a pair for a very good price. Why would 245/40/18 affect by only 1.6% and mine would be 4%?

40% of 245 as opposed to 40% of 265

40 being the height of the sidewall as a percentage of the tread width which affects the overall diameter of the tyre.

245/40x18 has a circumference of 2052mm
265/40x18 has a circumference of 2102mm

265/35x18 has a circumference of 2019mm

Russ

 

[rml]

Christ...we are just mere mortals

 

[sidmon]

Ahhhhh....I see. Always thought the 40 measurement was an exact measurement of the size of the sidewall....not a percentage measurement. Hence I was confused about 245/40/18 affecting the speedo differently to 265/40/18.