Have you guys tried willtheyfit.com? As long as you know the rim offset and wheel/rim sizes for both existing and proposed wheel/tire combo, it will tell you what CHANGES to expect. In other words, how the gap around the arch will change (tire height), additional space gained/lost on the outside AND inside of the new tires. It won’t tell you if it will rub (it’s a generic application and has no way of knowing where your suspension components are) but, if it tells you you will lose 10 mm on the inside, and you think you only have 10 mm of clearance, then you have a better idea of what spacer will make you comfortable. -Dom