AJP turbo said:
255 40 20 and 255 45 20 are the same width....what are you talking about?
I'm sure you find it hard to believe, but I doubt you know everything.
according to 1010tires a 255 45 r20 can safely handle a max wheel width of 9.5 inches, while a 255 40r20 has a maximum of 10 inches.
a tech told me that aspect ratio becomes a concern with certain tire sizes, the taller the tire the narrower the effective 'safe' width.