I got a set of 7.50 X 20 Denman Highway Express tires for the front of my '39 for Christmas. I compared them to the ones that were on my truck originally and they are a lot bigger. They fit the rim but the outside circumference is about 5" wider overall than the original 7.00 X 20 tires. The truck is in pieces so I cant mock them up. Does anyone know if they will rub the front fenders? Can anyone tell me why 7.50s are so much bigger than 7.00s? Can anyone tell me what the 7.50 or 7.00 means? I am an idiot when it comes to tires. Thanks