That is probably true, you could probably go as wide as a 305 on a non-stock rim. The 6.5" width rim will not safely hold the 305 width. Also, the second consideration is height. A 305/75/R16 might FIT and may not even rub. However, you might run into a problem with bottoming out when turning into driveways etc. If you want the wider look, use a lower profile tire like a 305/60 to prevent this.
As is, The largest tire Ford says will fit on a standard f-150 and 16 inch rim (I.E. xl, xlt, or non-sport package) is a 275/70/R16

 

That is bs click on my link below to show you 305/70/16 on a stock 97 f150 with NO LIFT NO TORSION BARS ADJUSTED.

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97 F150 4X4
4.6 V8 K&N Filter
Manik Grill Gaurd with 2 KC daylighters
American Racing Baja rims
Goodyear Wrangler MT/R 305/70/16 Dual Exaust with 40 series Flowmaster
Panasonic DF-600U and MTX Thunderforms with MTX 6000 in it with a MTX Amp

Web Site http://hometown.aol.com/steveng0143/...sBlack4X4.html

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