Alright so I feel really dumb asking this but

[Goolsbymd]

Im buying new wheels for the truck 20x10s 8x170mm(?) and looking to wrap them in 37" nitto terra grapplers and I never learned how to read the stupid things just always did the 37x13.50 deal, so im guessing 355/60/20 Load "D" O/D 36.8 is what im looking for??

[fordmugg]

try this Tire Size Converter

[smotrs]

Or if you feel like calculating it yourself, use the following formula;

Width x Ratio = Section Height
Section Height x 2 = Total Section Height
Total Section Height + Wheel Diameter = Tire Diameter

So, for a 325/65R18 tire, you would do the following,

325 * .65 = 211.25 mm
211.25 * 2 = 422.5mm
422.5 + (18*25.4) = 879.7/25.4 = 34.63"

Remember, convert your wheel diameter to mm by multiplying by 25.4 and convert the total mm back to inches by dividing by 25.4 which you can see I've done in the formula above.

[Goolsbymd]

355/60/20 Load "D" O/D 36.8

Now im assuming O/D is outside diameter, and i know they round up so those are 37s, which im looking for, but the 355/60/20 im guessing the 20 would be 20" wheels (sorry thinking out loud), the 355 breaks down to 14"? and the 60 8.4"? So 14" across and 8" from wheel lip to top of rubber?? So these would be ideal, right>

[Eric]

I put 8 ply (load range d)tires on my truck and I never will again. I don't know how much hauling you do but I would seriously look at 10 ply tires (load range e) Just my

[smotrs]

Originally Posted by Goolsbymd

355/60/20 Load "D" O/D 36.8

Now im assuming O/D is outside diameter, and i know they round up so those are 37s, which im looking for, but the 355/60/20 im guessing the 20 would be 20" wheels (sorry thinking out loud), the 355 breaks down to 14"? and the 60 8.4"? So 14" across and 8" from wheel lip to top of rubber?? So these would be ideal, right>

If what your looking for is 37's, then yes, those would be ideal. The 355 represents the tires overall width, the 60 represents the height of the tire from rim to tire tread as a percentage of the width of the tire, so 60% of 355 (13.97in) is 213 (8.38in) from rim to tire tread. Multiply that by 2 because you have a bottom section and a top section then add the wheel diameter (20in) which gives you a total of 934 (36.77in). Which makes it a 37in tire that is 14in wide at it's widest point.