Looking to replace the winter rubber that came fitted on my 1998 XJR with some summer stuff. The car has the stock 18"x8 Penta alloys, and the winter tyres are the factory recommended 255/40/18.

Looking at summer tyres there seems to be very little choice in this size. There are however more choices if you look at 245/40/18. Would this tyre size cause any issues or am I better off sticking with the stock size?

Cheers

 

Current size is 661.2mm, new size would be 653.2mm

Your speedo will be 1.2% too fast

When your speedo reads 100kph (60mph) you are actually traveling 98.8kph (59.3)

It should be fine, might help you stay a little below the speed limit too!