Tyre Sizes

[Rixtar]

What looks chunkier and bigger, 265/70/R15 or 31.5/10.50

Also can you put 265/75/R15 on an unmodified 2nd Gen and are they bigger?

[codlord]

By my calculations 265/70/15 = 29.6" diameter and 10.43" wide

so 31x10.5 15's are bigger in both diameter and width.

265/75/15 = 30.64" diameter and 10.43" wide

And both should go on an unmodified surf - I think the 31x10.5 or equivalent are about the biggest you can go without putting up with some sort of rubbing on wheel arches or fitting some sort of lift kit.

basically...
265 = mm width
75 = sidewall height as % of width
15 = wheel size

so 75% off 265mm is 198.75mm
times by 2 for both sidewalls = 397.5mm
convert to inches and add the wheel size - gives you diameter