So I have a 07 1500 with a hemi 4x4 qq and factory 20's... Since iv been reading everywhere it says it takes 1,000 off my 8,500 towing capacity... But when I did some research it says it if I put a LT tire on the truck it bumps it up too 8,400 ibs.. Right now I just have a mastercraft 275 60 r20's on it... SO is that true?

 

I recall that the factory 20s take away from the tow rating, because they make your gearing taller. I can't help you with the tire question... I suggest searching the 3 gen forum. Welcome to DF.

 

17" base 5.7L V8 gas MDS (EZB) A5 545RFE 5 sp AUTO (DGQ) 3.92 6,700 1,360 5,339 3,118 2,220 3,900 3,900 14,000 8,500

20" 5.7L V8 gas MDS (EZB) A5 545RFE 5 sp AUTO (DGQ) 3.92 6,700 1,260 5,440 3,160 2,280 3,900 3,900 13,000 7,400

LT 275 5.7L V8 gas MDS (EZB) A5 545RFE 5 sp AUTO (DGQ) 3.92 6,700 1,290 5,412 3,152 2,260 3,900 3,900 14,000 8,450



I found that... The end is the tow ratting....

http://www.dodge.com/bodybuilder/2007/docs/dr/mlup.pdf

so the lt275 means if I upgrade to that tire it gives me a better tow ratting at 8,450 I am guessing???

 

LT tires are available in C (6 ply), D (8 ply), and E (10 ply) ply ratings. A higher ply yields a stiffer sidewall, higher psi rating, greater weight load capacity and thus a safer tire for towing.

Don't know how that would change your trucks towing capacity though when staying within the same size tire.

 

It isn't wheel diameter that makes the gearing effectively taller or shorter. It's the tire diameter. 20" wheels are heavier. The tires may be, too.

 

I was told from a mechanic that towing capacity was based on braking power and capability which makes sense. No, matter what your truck can pull, it has to be able to stop safely. If your going to tow that much weight you at least want a D rating on your tire. I run an E rated tire although the higher the rating, the rougher the ride due to sidewall stiffness.