Tire size dilemma

[ghohouston]

My 97 f350 SRW is in need of some tires. Truck has 4:10's, zf5, stock height, riding on stock alcoas. Currently, running 235/85/16's. I either need to re gear to 3:55's, or go to a bigger tire, according to everyone I ask, because the tach sits around 3,000 rpm's at 80mph, which is the trucks average speed. Since I need tires anyhow, I think I'll just go bigger for now. The most lift this truck will ever have is the shortest rsk (2.25 inches I believe) and a super duty spring swap. I don't have a need for mud tires or anything like that, but once again l, I have to bring my rpm's down, and don't want to hurt my fuel mileage. So what would psa recommend for tires (brand and size).

 

[lincolnlocker]

you can easily fit a 285 /75r 16 under there with no rubbing issues.. i think i had 315/75/16 on my old 97 1 ton gasser... no rubbing either..

live life full throttle

 

[ghohouston]

Okay, any idea where that will put my rpm's around 80? I'd really like to bring it down closer to 2,000 rpm's.

 

[lincolnlocker]

Okay, any idea where that will put my rpm's around 80? I'd really like to bring it down closer to 2,000 rpm's.

i think you would need a 40" tire to get it even close to that without a gear swap! lol

live life full throttle

 

[Strokersace]

Mine with 33's, 3.73's, and an auto is right at 2k @ 70mph. At 80, I'm 2300-2400 rpm. Same range when I was on 35s and 4.10s. Your 5spd will be 200-250 rpm higher.

As Jake said, it'll take a big tire if you're not referring.

You're going to want 3.55s and 35's to accomplish anything close to 2k @ 80. I don't know if you'd like the driving characteristics of it though.

 

[ghohouston]

I hate these gears! My 02 model had 3:73's and stock ish sized tires, and turned like 2,200 at 80. Maybe I need to pony up and do a SD axle swap...