What size tire on a 7" rim?

[Mr Nice Guy]

What is the widest tire that can be safely put on a 7"rim? My brother is building a 240sx with a SR20DET that will make about 390 RWHP (lots of turbo goodies) and wants to put the widest tires possible. He bought some 16X7" rims and wants to get the most traction possible. I was thinking back to my old RX7 and 240sx and I was thinking 225s were the widest that would go on those rims anyone know for sure. Any help would be greatly apreciated.....Thanks in advance.........Later

[Injuneer]

I generally use the spec sheets at Tire Rack as a guideline. Each manufacturer sets its own recommendations, and it can vary for different tire lines from the same manufaturer. I find that Dunlop seems to have wider tires that seem to fit on narrower wheels, for some reason. They make an SP Sport 9000 that allows a 245/50-16 on a 6.5-8.5" rim. The Michelin Pilot Sport shows 255/50-16 as acceptable on a 7" wide rim. That would give you the same footprint, or slightly wider than came standard on the 4th Gen F-Bodys with the "performance" tire option, alhough the F-Bodys used 16x8 rims. If you look at "road racing" tires like the ones sold by Hoosier, you are more likely to be limited to a 225/50-16 or 225/55-16. Those tires are "measured" on a 7" rim.