Might be stating the obvious (to some) but something I didn't realise until I started trying to pick tyres for aftermarket wheels is that the profile figure - e.g. 40 - is 40% of the width.
So for a 255/40/17 tyre - diameter is 255mm, profile / side wall is 102mm (40% of 255), and radius is 17inches.
Learning this made it all make a lot more sense to me. I also have this graphic to refer to. Can't recall where I found it but it's now saved on my desktop!
I also wanted a chunky looking tyre with a solid side wall and after going 245(F) / 265 (R) , have since switched back to 235(F) / 255 (R) as I found the handling was noticeable more boggy and I use the car for fast road and track use. For ref, these tyres are on 18" BBS LMs.
By
sumshiftyguy ·
see three zeds in the space of 10 minutes today
1st was a white/ maybe silver near bromley town center at around 740 pm this evening
2nd was black on the a222 near chislehurst golf course 10 minutes later
3rd was yellow about 15 seconds after the black zed heading in the same direction