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Early 1999 Ford F-350 7.3 6-Speed CC LB SRW
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Discussion Starter · #1 ·
I have a an E99 F350 7.3 4x4 Crew Cab Long bed SRW. It has the ZF6 transmission with 3.73 gears and a 2inch leveling kit. It also appears to have a 3-stage chip, which I haven’t played with much yet. It currently has 285/70/r17 wheels and BFG KO2 tires. The tires aren’t in bad shape but the rears are D-rated and the fronts are E-Rated at 121, so neither is the right load rating for the pickup. The chrome wheels I have now are also peeling a bit and need some tlc. I bought some 16 inch stock wheels, had them powder coated, and want to get some new tires and I’m not sure whether to get 265/75/r16 or 285/75/r16?

I have read and searched the site a lot and would love to hear some opinions about which size might be better? I know the 285/75/r16s will feel very similar to what I have, and look good, but I am wondering if I will prefer the added power of the 265s?

I bought it back in September to tow my 7x14 12k dump trailer (3000 lb empty) because my previous 1999 F150 4x4 with a 4.6 didn’t even like towing that thing with a load of branches and tree limbs, much less with a load of sand or gravel. I know my max GVRW of the trailer is probably about 10,000 lb, so I don’t plan to ever max-out the trailer.

I use the truck mostly to tow the trailer with leaves, branches, or the occasional gravel or junk run, go camping with my family, or for projects on the weekend. It is not a daily driver really. We get a decent amount of snow here in eastern Washington most years, so if it snows a lot, I will drive it to work occasionally. Also sometimes just because I don’t want to drive my car.

I appreciate everyone’s thoughts and opinions!
 

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Stock tire sizes for your truck were 235/85-16 and 265/75-16, 31.7 inch and 31.6 inch diameter respectively.
You can fit 285/75-16 on it with no problem, but the diameter will be slightly larger (32.8 inches) and your speedometer may be off a bit.
Your 285/70-17 tires are 32.7 inches diameter, so if your speedometer has been adjusted to that size (done with a scan tool) the 285/75-16 size will result in the same speedometer reading.
As far as tread type, I run Cooper Discoverer AT3s on my truck year-round and get good performance from them. If you're really concerned about snow performance, a narrower tread would perform just a big better.
Definitely get E-rated tires which were the original load rating on either stock of the sizes.
 

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Early 1999 Ford F-350 7.3 6-Speed CC LB SRW
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Discussion Starter · #3 ·
My speedometer seems to read almost dead-on a GPS with the current wheel/tire combo of 285/70-17, but I really doubt that the speedometer was adjusted. I think that the original speedo reading probably was just a little optimistic, as it seems to be with most stock speedos. Hard to say on that though.

I had Cooper Discoverers on my F150 and they seemed to be a great tire. So I think that would be a great route. The AT3s look like they have a great tread-pattern for year round driving.

The pickup feels a little sluggish on acceleration with the current tire/wheel combo and if I am on a really steep grade I feel like I need to be in 2nd gear if the speed limit is lower than 40. Wondering if I will get some of that acceleration back with the lower diameter tires I guess? Or should I just turn up the chip?
 

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If you go with the 265/75-16 tires, the tire diameter will be less than you currently have, and your acceleration will improve.

If you use 285/75-16 tires, the tire diameter will be close to the same as you have now, and the acceleration will be about the same.
 
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Early 1999 Ford F-350 7.3 6-Speed CC LB SRW
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Discussion Starter · #5 ·
I ended up going with the 265/75-16 tire size with BFG KO2s. They look great on the pickup, accelerate a little better, and they are much easier to turn at low speeds. Thanks for the info and advice!
 
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