The largest size tire that fits under an unflaired front fender is a 245-50 by xx diameter, usually on a 9-1/2" wide wheel as maximum. 18" fronts are uncommon; more common are 16" or 17" . In the rear, a 12" wheel mounting a 335-35x 17 or 18" tire will clear. Note that some hammer-clearancing of certain areas under the front fenders must be done, and the fender lips must be rolled under to keep from catching the edge of the front tires during hard cornering. Note also that the Pantera body dies wree apparently not symmetrical; more problems in clearance tend to exist on the left side than the right, and the right suspension tabs (front & rear) may be offset outboard by an inch or more on some cars. I would suggest using one of the known Pantera suppliers as a source of aftermarket wheels, just to keep from having to "re-invent the wheel" in a literal sense. I do know that Pantera Parts Connection in Reno did supply a single set of 18" wheels for a stock-bodied Pantera in 2001, and they did fit but were extremely expensive at the time. Their catalogue & prices are on line. Other suppliers may now have 18" sizes available but it might take a phone call to verify the size etc. The owner of this website may have such as well.
