I have seen lots and lots of posts that assume that moving between 255-265-275-285 wide tires actually means moving roughly 10 mm in tire width. This is not so. Not by a long shot.

So how can we know? Only TireRack, I think, offers one-stick-to-all-tires measurements and so they are the only reliable source of info.
Example: https://www.tirerack.com/tires/tires...omCompare1=yes

The results can be very surprising. The differences are much bigger than those in diameter. Wheel width does not matter for tread width. It does for section width.

255-70 tires actual tread width:
7.5 Duratrac
7.7 Destination AT2
7.8 Destination AT and MT2
7.9 General X3
8.2 BFG KM3
8.4 BFG KO2
8.6 Cooper STT Pro

265-70 actual tread width:
8.0 Goodyear Trailrunner
8.2 Duratrac and Adventure with Kevlar; General ATX
8.3 stock Dueler
8.4 Dick Cepek Extreme Terrain
8.6 Destination AT2
8.7 Destination XT, Cooper Discoverer AT3
8.8 BFG KO2
8.9 Sumitomo Encounter AT (sibling of Wildpeak AT3W)

275-70 actual tread width:
8.4 Destination AT
8.7 General ATX
8.9 BFG KO2


285-70 actual tread width:
8.9 Discoverer AT3 XLT
9.0 Grabber ATX, Destination AT
9.2 Destination AT2, Toyo Open Counrty AT2, Dick Cepek Trail Country EXP
9.3 BFG KO2, Dick Cepek Fun Country
9.6 Wildpeak AT3W/ Encounter AT

SO...you can have an 8.0" 265 and a 8.9" 265.

285 Discoverer AT3 is the same tread width as 265 Wildpeak At3W.
255 KO2 is wider than 265 Duratrac
255 STT Pro is quite a bit wider than the stock 265 tire
255 Duratrac is not 10 mm narrower than 265 Widlpeak, but 35 mm!

For 265/60/18 (for my GX stock size), tread width variances are ridiculous.

All are P-metric except KO2:

Dueler HT (stock) = 7.1
GY Adventure Kevlar = 9.8 (!!!!)
BFG KO2 (LT-E) = 9.1
Michelin Defender = 8.3
Yoko AT G015 = 8
Conti TerrainContact AT = 9.1
REVO 3 = 8.6
Firestone AT-2 = 8.8

It is as if these OEMs just don’t care about standards!

Great info! Yeah, I've noticed nearly an inch difference in overall heights for various tires in the same size between not only manufacturers, but also between their various tire models in some cases.

Throw in different offsets and rim widths and you can have a 285/70/17 fit with no mods in one instance and rub hard in another.

I usually start with the tire I want and start looking at the actual measurements before deciding on size/lift/mods.