Comparing 255/85R16 to 265/75R16

With 2,500 miles on the new 255 Cooper Discovery ST/Maxx — I’m ready to provide some comparisons to the 265’s they replaced of the same make and model tire. What this won’t be is a review of the Cooper’s… I’ve already done that ;)

In their short life so far, they’ve seen dry, wet and snowy pavement. They’ve bombed through sand, sailed through mud, clawed over granite boulders and crunched their way through snow and ice. Here’s what I think the pros and cons are of going 255 vs. 265 (if you can fit them) — specifically for the second generation Xterra.

255 Wins

  • They’re smoother on-road (and off) and the steering is lighter. I think the improved ride comes from having more sidewall and the steering change in less tire width.
  • They don’t follow grooves and indentations in the freeway like the 265s did.
  • They’re taller (I gained 1/2″ in stance). But do require the melt mod. “The forums” tout you can run these without. Maybe if you never go off-road. But under hard braking and turning — they rub. The rears also rub on the frame rails at full stuff (three-wheeling). So do the 265s, but the 255s are worse.
  • Mechanical keying and tire deformation is significantly better. And with the additional clearance and sidewall height — you can air way, way down. Think gecko fingers.
  • They dig more in soft terrain. This is sometimes a pro (water-logged mud and clay); but is also a con (sand).
  • They’re less prone to hydroplaning. In fact, it might be impossible (trust me, I tried).

265 Wins

  • Acceleration, braking and gas mileage are all better on the 265s.
    • I averaged 13.98 MPG on the 255s, with 11.8 MPG being my worst and 19.1 MPG being my best. Over the same number of fills on the 265s, I averaged 14.06 MPG. 11.6 MPG was my worst and 17.1 MPG my best. However, if you throw out my only 19 MPG fill on the 255s (which I got doing a non-stop, 25 MPH roll in 2WD in the desert), then the 255 average goes to 13.63 MPG with the low being the same and the new best being 14.58 MPG.
      So in other words, expect a half-mile-per-gallon drop at a minimum. My city numbers are pretty similar — but where I use to be able to get into the 17-19 MPG range on the highway — that’s now just a distant memory. Getting over 14.5 MPG on the highway now is a victory.
      *All numbers corrected from what the odometer showed*
  • All the second generation Xterra speedometers (even those that came with 265/70) are calibrated to the 265 tire size. So your speedometer, odometer and trip gauges are spot-on with the 265s, and slightly off with the 255s (online calculators say about 4.26%. Compared to my GPS, it looks closer to 3.85% to me).
  • Cornering in the rain is a lot more confident on the 265s. I can break the 255s loose on wet pavement.
  • The 265s have less roll in the corners. The additional sidewall that improves the ride also softens the truck in the corners — giving it more body roll. It’s about the difference of having 150 lbs. on the roof rack on the 265s.
  • While the 265s were a little mischievous about following grooves in the California freeways (which the 255s do not), they also seemed to track better on smooth stretches. In other words, the 255s wander a bit more.
  • I’ve found three different weights published for both tires. One of them says the 255s are lighter (hence my earlier comments). The others, including Cooper website (today), says the 255s are heavier.

Your Call

  • 255s are visually skinnier. I like it. You may hate it.
  • The 265s bulge a bit more on OEM rims, while the 255s have a more squared-off profile. If you’re lifted with out camber bolts (like me) — the 255s outside edges wear better than the 265s.
  • Both fit in the stock spare tire location.

The Verdict?

265s are the perfect size for the Xterra and will go 90% of the places a 33″ tire will go (255 or 285). That said, if you’re looking for that extra 10% capability and willing to sacrifice a few on-road traits, the 255 is a hard tire size to beat. And a hands-down better size than 285/75R16 in my opinion.