I've got an '02 F-250 SD 4x4, and I'm about to lift it 8" and put 38's on it, but the tire & rim choices have me stumped. It's a problem of three factors, of traction, of rim width, and of tire tread width.

1. First problem is that besides on the road, this heavy truck will be seeing soft deep sand, and slightly deep clay mud (sometimes with, and sometimes without a bottom, the kind you'd find on a muddy farm road, or two track hunting trail.) The 38x15.5-16.5 (11.5" tread) would be the obvious choice untill you factor in airing down for the sand, hence the second problem.

2. 16.5" rims are bead poppers by design, and I don't think it would be much fun re-seating the bead on a 38" 10 ply tire. There is a 16" rim 38, but it's a 38x13-16 (10.0" tread). This would provide me the ability to air down, and even maybe do a beadlock conversion.

3. Even though the tread width between the two tires only varies 1.5", the 15.5's sidewalls would also contact the sand providing more floatation than the 13's, correct? But I also remember seeing somewhere that when aired down, a taller & narrower tire will have a greater contact patch that a wide tire, is this true?

Or is the whole tread width/airing down/traction even an issue because these tires will be supporting such a heavy truck? I do realize that the 38x13's do have a lesser load rating, but this truck won't be seeing much towing (besides the trucks I pull out *grin*). Any insight into any of my 3 problems would be greatly appreciated!!

Super Swamper TSL Radial 38x15.50-16.5 (37.6" tall x 11.5" tread 3640lbs. max)
Super Swamper TSL Bias Ply 38x13.00-16.0 (37.8" tall x 10.0" tread 2700lbs. max)

 

Will 16's even clear the 250 chassis brakes? I don't think they will, check on that first.

Chris

79 F-150 Lariat: Long-bed, 2wd, 460 (intake, headers, cam, early heads), C-6 (shift kit)
79 Mustang: 460 swap under way, balanced rotating assembly, forged pistons, truck rods, c-8 heads ported, Lunati solid lifter cam, more stuff...
98 Chevy Silverado ext. cab 4x4 (work truck)
95 Lexus SC300 (wife's baby)

 

16's are stock on a 250, I even double checked with Mickey Thompson's tech line and they OK'ed it, so until futher notice, 16's fit.

 

Hopefully this will help a little, the reason a wider tire actually will have less "direct" contact when aired down is the center tends to lift more/higher. A thinner tire will do this, just not as much. Unless your really, really heavy, I don't think you would notice much difference between the two sizes in the sand, width helps but tread design also makes a big difference in helping the tire float or dig. High HP, nothing beats a paddle, low HP, not really heavy, a tight A/T type or aggresive street tread in the wide variety (12.50) seem to do best in sand.

 

 

Thank you Chuck P! Looks like I'll be going with the 38x13-16's then! Actually the 38's are only going to be for off-road use in mud and in the back country. I got to thinking why am I even considering taking an extreme mud tire into the sand when I'll be running a set of 37x12.5-17 BFG MT/Ko's for the street? The MT's won't be as aggressive as the Swampers (less likely to dig in the soft stuff), 17's still have the ability to air down safely, and they're almost the same width as the Swampers. Thanks to all who replied!