Slick tyre size... talk to me

[m3ben]

Morning chaps,

I have a spare set of wheels that i would like to put some used slicks on for track days, but as the way the sizes are displayed is different im not sure which size would suit me best.

So, which size of slick would be closest to a 225/40/18 road tyre?

Thanks in advance guys

[majordad]

ASk Protyre/Michelin or google Michelin

[TheEnd]

There's a 240/640/18 as a common size.