Im new to the diesel truck game. (and this forum which Im glad to have stumbled upon.)

I just purchased a 1991 f-250 w/a 7.3 diesel. It has a set of 235-80-16's on her.

My question is how big of a tire can fit without lifting the truck, damaging the drivetrain, or rubbing of course?

265's, 275's, 285's, 33x12.50's, 35x12.50's or bigger maybe?

I just want the truck to look a little meaner. Thanks in advance and again glad to be part of the community.

 

well someone's gotta say it... There is a search function for a reason. This has been discussed many times. I myself am also guilty of being lazy and not wanting to use it, but this would be a common one to find. Check it out, and good luck to ya

 

Not being lazy. I used the search and have found useful info but can not seem to find a definitive answer to my question.

Just looking for a little help in making the right decision. After all load range E tires are very expensive and I don't want to make a mistake.

 

Assuming its a 4x4, you can run 33's comfortably, and 315's will fit, but they're a snug fit and you wouldnt want to go offroading much with them

 

From what I have seen 285/75R16s fit quite nicely on these trucks with no lift. Is it a 4x2 or 4x4?

 

Thanks for the feed back guys. I had no idea something that big would fit.

It is a 4x4 and I will do a little off roading from time to time. nothing like some of the guys I've seen on this forum, but I will get her dirty.

I will mainly use it as a winter truck and to tow my classic cars with when needed.

if i remember correctly increasing the diameter of the tire will increase my gear ratio slightly. So just for an example (not correct #'s or math) if I put a tire on that is 3" taller than the stock tire and the truck has a 4.10 gear ratio the taller tire will change the gearing to say a 3.90?

Does anyone know of a website that would allow me to type in tire sizes and give me these gearing specs?

 

- Dirt Road Magazine - Gear Ratio Calculator - (dirtroad.com)

Theres some calculators there. The 1st calculator is the one you want, and then you use this formula

A - B = C

B - C = D

A = New gear ratio from calculator, B = Current gear ratio, C = Computed difference in ratio, D = Equivalent gear ratio

Using your current gears/tires (31's & 4.10) if you went to a 35, you would need a 4.63 gear to stay at stock rpms. Take the 4.63 (A) subtract 4.10 (B) and you get .53 (C)

Now take the 4.10(B) and subtract the .53(C) and you get 3.57(D) which would be your equivalent gear ratio with the 35" tires on stock gears.

 

thanks for all the help L.Ward, may the 4x4 gods smile upon you! By the way love your avatar!

Im thinking I may go with the 285/75-16's they will through the speedo off by 3.9 mph and give me a drive ratio of 3.78. Theirs better sizes that wont change things up so much but the other sizes dont seem to come in load range E's.

If I do go with the 285's they wont damage the drivetrain or 4 wheel drive system right?

 

The 285's will be fine, ran them on my 97 psd for years. I think they look better than the stock 235's. I don't think they will make any noticeable driving difference in your truck, didn't in mine anyway. Mine had 4:10 and an auto.

 

Great news mine also is a auto but with the 3.55's and limited slip.

I was thinking about some Bridgestone A.T. Revo II's anybody have any experience good or bad with these?

Or maybe some Firestone Destination A.T.