I have the stock size 235/85/16s on the truck now but would like to go larger for better fuel economy and performance, namely braking and trailering. I was thinking either 265/75/16s, which will be wider but actually a smaller overall diameter than stock, or 285/75/16s which are much larger in all dimensions. My question is will the 285s fit without rubbing? The truck is a 85 F250 XL extra cab long bed 2WD with 4.10 gears. Thanks for the help.

 

235/85/16= 31.7"x 9.3" = base line 4.10 to 1 gear ratio
265/75/16= 31.6"x 10.4"= 4.11 to 1 gear ratio
285/75/16= 32.8"x 11.2"= 3.96 to 1 gear ratio
255/85/16= 33.1"x 10" =3.93 to 1 gear ratio
ok
I did that so we all have a better idea of what you want and probably what you will get. In fact I recomend by the small differences above that you get a gear vendors (under/over dirve) or change your rear end gears to 2.75 to 1 if you want milage over a simple tire change you will not see any inprovment from the tire change you will not be able to tow tow much with a 2.75 to 1 ratio. The best thing all around would be getting a overdrive.
final drive raito with a .75 overdrive would be 3.075.

 

Yes, I know all about the overall diameters and will most likely be changing the rear end to a 3.07 since with the current setup 65mph on the freeway is 2900 rpm, not fun. The 3.07 rear end will get me to 2100rpm at 65 and I'm hoping slightly larger tires will drop me below 2000 but I'd like to know if they'll fit without rubbing. I've love to get a gear vendors but I don't have $2000 to spend on the truck right now. Thanks for the reply but my question still remains: Will the 285/75/16s rub on my truck?

 

how much do you tow with this truck? would you like to over 5000lb? you will not be able to tow as much with a 3.07 to 1 gears as for tire fitting or not Your best bet is to take the tires off and measure out the demensions or have a local tire store do it for you. I can fit 35" tall tires on my truck with a stock suspension. also I can't tell you how worn out are your springs are and what will work with them.

 

I have a 97 F250 HD that came stock with 235/85/R16's and I switched to 285/75/R16's. The only thing I had to do was grind off the little tooling tab at the corners of the bumper. Having done that I have had know problems. I tow a small 5er and the truck handles it well. I would recommend that you go to a wider wheel if you jump up to the 285's, at least 8" wide.

 

Im running lt305/85/r16's 10ply with 3:55's for the winter,no lift and they dont rub and i average 70 mph at 1900 rpm,in the summer I run 35x12.50x16.5 and they do not rub either,I pull lowboy with a bobcat on it and do fine until i come to the mountains but even then i drop no lower than 3rd gear and stay right at 55 the whole way up the mtn.I do believe im gonna change over to a little lower gear this summer though.

 

285/75 R16 fit right on my 4x4 86 with no problems.

The Dueller Mudders were even 33.1" tall.

The taller tires will not help you in braking though, they will be harder to stop than the short tires.
The taller tires will also not help you drag a big load up a hill.

They will help you go faster for the same RPM's though. So if you drive the same speeds you are now, you may see some improvement in milage.

A 31" tire you have should give you 46 MPH at 2000 RPM.
A 31" tire you have should give you 67 MPH at 3000 RPM.

A 33" tire should get you about 48 MPH at 2000 RPM.
A 33" tire should get you about 72 MPH at 3000RPM.

 

The wider tires will help with braking as I've found the truck will lock the tires without to much difficulty and I'd like to stop that. I will be towing 5000lbs at the very most, my car weighs 2700lbs plus trailer, tools, spare tires, etc. If I have to tow more than that I'll just go slower, but it'll be rare and I doubt I'll be going over many mountains with a big load. I work at Sears now and have compared tire sizes by rolling the new tire up to the truck but I can't mount them without paying for them and it's pretty hard to tell if the tire will rub when turning just by looking at it. Thank you all for your help and I think I'll have to go for the 285s. I don't want to go much faster but I hate having to run the truck almost at redline just to attempt to keep up with traffic, not to mention 13mpg on the freeway sucks.
Zamboni, you bring up a good point that I was actually going to ask about, I'll have to look around and see if I can find wider wheels, although that makes the cost go up by that much more. I'm used to sizing low profile tires and can tell you exactly how wide a wheel you need to fit a 275/35/17 but it gets a little fuzzy when the sidewalls get huge.

 

My 285's are on stock wheels. If you wanna see them look at my gallery.

 

Im not saying it can't be done. Usually stock wheels are 7" wide and with a 285 tread width the tread bows a tad giving you less of a contact patch and a smaller wear area. It is just a suggestion. I went to 16x8's and am very happy with them.