The 1-5/8" whitewall is exclusively on the 235/75R15 Firestone 721. The 225/75R15 tire comes with a slightly narrower 1-3/8" whitewall, and the tire is not "Extra Load" rated, though it's perfectly fine for a smaller '81-83 Imperial or Neal's similar '83 Cordoba. Chris in LA (Actually in Chicago today) 67 Crown 78 NYB Salon Neal Herman wrote: > Two years ago I put Firestone 721 radials on my Cordoba, which is based on the > same platform and is roughly the same size as the Imperial. I believe the > whitewall width is 1-5/8", and they look fabulous on the car. I also stepped > up a size to 225/75R15, and have had no trouble at all with scraping of the > fenders or anything like that. They seem to ride smoother than the old > Sears/Michelins I had, that only had about 7/8" whitewall.