I have an 85 F150 2wd LWB Supercab wih 5.0L AOD and 3.55 rear. My current tires are 235/75/15 and they are 10 years old or older. My father-in-law just got a used set of 10.5 x 31 tires and he wants $60. I'm getting mixed reviews of this size in my search and want some fresh opinions.

Am I asking for trouble with this size? And does anyone have a pic with a 2wd and these tires?

BTW: I'll be using stock wagon wheels with the trim rings.

 

I do know they are going to rub(the radius arms) if you put them on the stock rims, and they will also wear the center of the tread out faster on the stock rims. You need to get aftermarket 8 inch rims to run these tires at all.

 

I have a set of 31x10.50x15 on my 87, when i bought it had them also and they were wore out, but they did so very evenly and are mounted on the stock rims. Yes they do rub when turned to lock but I get around pretty well with them.

 

FWIW had them on 7" wheels on an E150 with 3.50 gears, no issues but you may notice a difference due to the overall "gear ratio" change.... For $60 for a set of tires? How bad could it be? Add another "0" for new ones....

 

I run them on my shortbed truck on 8" wheels and haven't had a problem. Here's a picture.

 

I've got a set of 31x10.5x15's on my truck mounted on 8.5" wheels.

 

Looks Great Dave!

 

There were 3 different widths of these wheels. White 15 x 6, silver 15 x 7 and 15 x 8. Since you mention the trim rings, I'm guessing you have the silver ones, since the white ones didn't use trim rings.
A 31x10.50 really needs at least a 7" wide wheel to fit right, and 8" is preferable.
They may (most likely will) rub the radius arms at full turn, but just how often do you need the wheels turned fully, especially when moving very much over a crawl? They *could* rub on the underside of fenders (front more likely) over really big bumps, but that's usually not much of an issue.

 

86-down, the widest rim I can find offered was a 7 inch(the wagon spoke). I found a aluminum with little rounds holes in it offered around 1990 that was 7 1/2 inches wide. Maybe the later trucks had a 8 inch rim, but it looks like 86-down did not have one.

Each time I went to park my 80 in the parking lot with the 31-10.50 tires on stock rims, they rubbed the radius arms. You could feel the vibration in the steering wheel and hear it rubbing. In my case, since I parked it everyday in a parking lot, it rubbed twice a day for me.

 

As RW knows, I have a set of 8" wagon wheels w/a Ford stamp on them. We didn't find a P/N, so dunno what year they came on. Anyway, they have 31x10.50's on them and the tread seems to have worn fairly evenly. In fact, the tires look good on there. And, the radius arms have rub marks, but no marks anywhere else.

 

I've got 31x10.5x15 on a 2WD with no issues apart from some rubbing on the radius arms, but only when it gets close to full lock. Wheels are 15x8 from a 92 bronco

 

also depends on the tire specs, some 31x10.50's are 29.5" tall some are 31.5" tall with width's varying from 9.75" to 11". MOST 235/75R15's measure out in the 29-30" tall range and 8.5-9" wide, The only thing you'd really be gaining is width.

 

I'd run em without a doubt.

 

I do have the silver wagon wheels, but I'm unsure of the width. I think that I'll go ahead and try the tires and I'll measure the wheel width when I mount them. I actually dodn't drive the truck very often and I've even bought a 89 F250 4WD as a replacement, but I just can't seem to let my trusty 85 go.

 

Franklin, you are correct. The widest rim offered from 1980 - 1986 were 15x7" silver wagon wheels with trim rings, which Ford called "Deluxe argent styled steel wheels."

From 1987 - 1991, the Ford Bronco got these exact same wheels in a wider 15x8" version, but the red stripes on the trim rings were dropped in 1990. In the picture below, you can tell it is the wider 8" wheel because of the "step" between the rim itself and the trim ring. The trim ring would meet right up to the face of the rim on the 7" version: