original diameters are about 28-30", check tire conversion charts, the height isn't as critical as the width of the rim - 5.5" original ... if you're looking at modern sizes, do you have 15's or 16's? unless you go to real truck tires you're not likely to find anything 32" unless it's way too wide for the stock rims or you're using aftermarket modern rims, which will likely cause problems with full lock turns
Bill
