My 1994 came with P265/75 R15 tires. That is the only tire size listed on the sticker. Maybe it was specified as part of the package with the front Quad-shock setup.

The last tires I had on it were Yokohama Geolandar H/T-S in that size. When I went to replace them with same, they had disappeared from the warehouses, Yoko no longer making it. Tried special ordering another brand, I think it was Goodrich Long Trail, even though those were still listed as orderable, they were not - also obsolete. Seems that tire size is no longer made. Both the tire store and I separately came up with 31/10.50 R15 as a replacement size, within a rev or two per mile. Yokohama has all kinds of tire info on their site, all sorts of measurements, etc. After checking the Bronco clearance to front bumper through turn angles, and against wheelwell/frame, it looked good.

So I have 31/10.50 R15 Yokohama A/T-S on there now. No problems. They seem to be stiffer sidewalls, and start getting the All-Terrain howl starting around 45 MPH. That doesn't bother me, it's a truck. And I don't do any extended interstate driving with it. And my hearing is not the best anymore... what?

With the incredible proliferation of profiles and wheel diameters now, the number of tires that a tire mfg. has to make and keep warehouse stock in must have gone waaay up, compared to back when this Bronco was new!

 

Had the same issue when I purchased my Bronco and needed to get 5 new tires for it. So I wound up with 31/10.50 R15 BFG all terrain tires. Good on highway ... so so off road in mud. Haven't tried snow yet, been hoping to get up into the mountains but haven't gotten more than one day off in a row

 

265mm wide
Sidewall is 75% of the width.
15" rims

25.4mm in an inch
265/25.4 = 10.433"

10.433" * 0.75 * 2 = 15.65" of sidewall

15" rim + 15.65" sidewall = 30.65"


So, a 265 75R15 is a 30.65" tire that is 10.43" wide.
Most 31" tires are around 30.5".


In the end, a 265 75R15 and a 31x10.5 R15 is almost indistinguishable.

 

Those BFG's are just about as good as you can get now in loose sand.Especially aired down . Back in the "old" days there were a couple of brands on the market like "Maxi-tracs" and "Multi Tracs" that would outpull anything you could get in sand. And were decent in slick mud.

 

I put that size on my '89 F-150 a year or two ago. Looks like they are still available: Cooper Discoverer AT/3. Good tires.

 

I had the same problem when picking out tires for my Bronco. Previous owner had 31-10.5s on it. I wanted a P-metric tire, but had little options. I wanted new rims too, so I bought a set of 16" rims and got P265-70R-16 tires. They have almost exactly the same outside diameter as the P265-75-15s, and I have tons of options when shopping for tires.