As long as the total outside diameter of the tire stays the same.
My 91 Diablo as 335/35/17 in the rear. For me to go to a 20" wheel I would need 335/25/20 size tire. The original is 26.23" tall. The 20" rim tire would be 26.59" tall. A little more that a 1/4" taller is fine.
How do you find the height of a tire you ask?
I'll do it on my original tire.
335 multiplied by .35 = 117.25, then multiplied by 2 = 234.5, then divided by 25.4 = 9.23, the add the height of the rim (17") = 26.23
Remember a thinner sidewall would give an even harsher ride. (if thats even possible in my car LOL)