Need help on tires: 13 F-150 3.5L Ecoboost, 20” Gear Rims. I currently have 275/65r20 Terra Grapplers. My toe got messed up on the front end so 2 of them have almost no tread left on outsides. I don’t pull anything but a jet ski and lawnmower trailer so I don’t necessarily need “E” rated tires but I do like the size and the all terrain look. What would you recommend? Stay at the size I’m at? Go down to 275/60r20 and lower load rating? I’m also wondering if that would help with gas mileage. Computer says I’m getting 12.3mpg right now.

Nitto does make the Terra Grappler in a Non-E rating 275/65r20 but it's only about 9lbs lighter than the E's.

 

The primary advantage of E rated tires is that they are a tougher tire that will be less likely to fail if you drive off road or on rough poorly maintained dirt and gravel roads. A standard tire will carry more weight than your truck is rated for. You don't really need an E rated tire for the weight until you get into 3/4 ton and bigger trucks with GVWR at or over 10,000 lbs. If you drive off road or in areas where tire damage is a concern than E rated tires are a good idea. Otherwise stay with standard tires.

Unfortunately the larger sizes, and more aggressive tread pattern tires generally only come in E ratings. IME if everything is the same. Same tire size, same or similar tread patterns any difference in fuel mileage between standard tires and E rated tires is negligible. But going to a 1" shorter tire with a less aggressive tread along with a slightly lighter tire could see a 1-2 mpg increase on the highway. In city driving I just don't see it.

The 3.5 has a lot of torque and can handle bigger tires easier than the 5.0. But the gear ratio still matters. Not about fuel mileage, but performance. If you have 3.31 gears I'd go down to a smaller tire. The 3.55 gears will handle the larger tires you have now easier.

 

Stock size for my ‘11 Ecco is 275/65-18. It gets 1-2 mpg more on P rated tires than LTs. But it burns through those P rated tires by 30k. LTs have more tread depth to begin with and it’s gone 40-50k on them. I figure stock size LTs cost me no more than $.01/mile more than Ps, to run, and I get better sidewalls.

Also, 18” P rated sidewalls compared to LT feel mushy to me in crosswinds, trailering, and cornering. Am guessing that’s not nearly as bad with a 20” tire. But a consideration.

All terrain LTs are noisier. (I run BFG KO2 snowflake rated). Others say the ride isn’t as smooth, I don’t notice.

I’ll stick with a LT for sidewall protection and handling. If cost, ride and noise where priority I’d buy some nice P rated.

 

I looked tonight and I do have the 3.55 gears with the 3.5L Ecoboost......I was trying to figure out what rims I have and I think they are 20x9 18offset Gear Big Blocks.

 

Not to hijack this thread, but 10 ply vs radial? Looks like radial is more forgiving with ride comfort, would 10 ply reduce that for highway driving? Currently using Hankook Dynapro AT/M at 275/50/20 (I think). Wanting more beef to fill in the wheel wells, and I don't do too much off road driving. Someone on CL is selling a set of new Nexen Roadian 10 ply 305/55/20 for what seems like a nice price ($850), which i think after all my research would fit on a leveled truck, but not sure about going from what i think is radial to 10 ply. any advice appreciated.