change of tyre size

frosty984

Wrench Pro
Points
16
Location
Croatia, Bjelovar
Car
Yaris 1.0 VVT-i
Hi,
I'm thinking about changing tyres on my car, now they are 195/65 R15 with steel wheels and i would like to change it to let's say 245/45 R18 alloy...my question is...is that smart lol and how it will affect my speedo? And will there be any effect on grip and that stuff, its a rwd car, 1400 kg. Mercedes W202. Thanks for your help :)
 

Yugguy

Torque King
Points
507
Location
Rugby (expat Preston lad)
Car
Merc C220Cdi Elegan
Howdo. Google miata tire calculator, this lets you put in two sets of dimensions and will tell you the difference of speed etc. It is recommended to be within 1% of original

As to grip, there is the school of thought that going overly wide lowers grip iin the wet as there's less weight per square inch of tread.
 

SLEEPER

Pro Tuner
Points
562
to answer your question

The speedo will be out by the % change in circumference of the tyre.

1.51% means a 1.51% change in the speedo .

But thats all , generally changing this wont upset a standard rwd car unless it is by a lot say 10%+ .
After all the difference between new and worn tyres can be more than 1 %

Tyre size can be critical on awd/4wd vehicles when you run different size front to back If they are more than 1 % out it can damage the diffs/transfer box.
But again if they are the same but larger thats probably OK. ( mine is )
 

Similar threads

Top