Good afternoon, I tried searching this but didn't find conclusive enough evidence. I have a 2015 max tow 3.5 eco with 116T tires. I'm needing to replace the factory GY Fortitudes which I have actually been very happy with. I do lots of highway miles, tow a lot but not near my capacity, and hit gravel roads during hunting seasons. I am curious if stepping down to a 114T tire will hurt me, because on occasion this year I will pull a 9k pound camper from dry storage to our campsite, maybe 10 miles one way. I do not want to go to an LT E tire to prevent hurting gas mileage within reason which I have been very pleased with over the life of the truck.

My GVWR is 7000 and rear axle is 3850. I understand a 114T tire should be able to handle my axle weight but there's a voice in my head that says stepping down in load rating isn't a good idea. Any input is much appreciated.

 

My tires are stock size P265/60R18 Michelin LTX A/S with load index of 110. I one time overloaded them to 5,085 pounds on the rear axle when dragging a 21k gooseneck trailer 350 miles across the Texas Hill country. No problems whatsoever, but I was a Nervous Nellie that checked tire temps very 100 miles or so.

So I would say that if you don't overload your rGAWR, then there's no reason not to replace your tires with load index 114, 112, or even 110.

110 Load index = 2,337 pounds per tire or 4,674 pounds per axle, which a lot more than your 3,850 rGAWR
112 Load index = 2469 pounds per tire or 4,938 pounds per axle
114 = 2,600 pounds or 5,200 pounds per axle
116 = 2755 pounds or 5,510 pounds per axle

I like fudge factors, but my tires with load index of 110 have plenty of fudge factor at about 21% more weight capacity than required. 2337 pounds vs 1925 pounds required.

 

Smokeywren, your results are still valid (enough capacity), but don't forget the ~0.9 derating for "passenger" tires on "truck" applications.