Mine has 245/75R16s all around. Since it needs new rubber I was going to ask about running taller tires on the rear to help improve mileage. I know of at least one Vanagon guy doing this, and a guy in the 'hood with a Ford E350 has taller rears, 285s, I think. I'll have to ask him how that affects his mileage. Build sheet says 200mm rear axle, but that's all the detail that's available until I crawl underneath and look for ID tags or markings. If the stock rear end is okay I'm unlikely to consider a gearing swap unless the fuel mileage is abysmal (pleeeease, no). I did measure the fuel tank and it is the larger one. The van has a large space behind the tank and ahead of the rear bumper. I'll have to see about mounting a spare tire there instead of the interior mount that is stock in order to free up space for the camper build.