The speed rating also varies by tire size, the 275/55R20 has a T rating, or 118MPH, as well as being severe snow rated. Note that I'm pretty sure all duratracs are M+S rated, they just aren't all severe snow (or tri-peak) rated.

 

Yes, but that size Duratrac (275/55R20) is SL / Standard Load rated. You should mount XL / Extra Load tires at a minimum on the new Defender.

 

Not specific to the duratrac's but in terms of driving dynamics and the question of going plus size: I did the Johnson Rod 1.5" lift and went with BFG K02's in 275/60/20. After a 1000K miles highway, snow, dirt and gravel roads... (of course it's better off road) while slightly louder, I am extremely impressed with driving dynamics on road and highway. I do not see a down side in terms of height with the lift or tires. I think if you're selecting a slightly bigger size you will not experience any downside.

 

They don’t sell the duratracs from the factory because that would lower their fleet mileage numbers which they need to keep up as much as possible. And for all the other reasons cited about the Adventures being better for most buyers. If you live in snow country and want to drive during and right after storms, you should just get a spare set of wheels with winter tires. None of the three peak AT’s will be as good especially on icy packed roads. You could also look at KO2’s which are three peak rated, but again not nearly as good as a winter tire on icy roads.

 

Load Rating is a indication of toughness measured by the max PSI rating, XL implies 42 PSI, but both the 275's and 255's have a max of 50PSI. This would imply they both exceed the XL rating, no idea why it's not stamped on the 275's, guessing it's a certification/red tape thing. The 275's have the same load index (113) and max inflation pressure (50psi), so they can carry the same weight as the 255's, and are just as tough. The 275's also actually have a higher speed rating, so they are actually a higher rated tire.

 

Thanks again for the feedback thus far...I didn’t realize when I began this search that selecting a new tire would require this much research. I’m a rookie when it comes to speed ratings, load ratings and overall tire specs. Seems the easy answer is the Duratrac however there is a significant difference in the speed rating between that and my current Wrangler ATs. In the end I know it will come down to personal preference, hearing recommendations or getting input is helpful none the less.

The hunt continues...

 

​​​​​​It's not at all a "certification / red tape thing". XL tires are built differently than SL tires, reinforced with extra layers of material / thicker carcass and generally stiffer, especially around the shoulders, to better withstand extra loads, bumps on the road, curb strikes, rock incursions... They may look similar on the outside and the numbers on the sidewalls may sound deceivingly similar as well (xxxx lbs at 50 PSI max simply means the tire is guaranteed not to blow up until you reach 50 PSI, not that it should run anywhere near that pressure.) but SL and XL tires are quite different in the way they're built, in the recommended inflation rate that's directly related to their strength, and in the additional stiffness that can also greatly affect ride quality and speed rating between otherwise identical - or nearly identical - sizes, such as the above examples.

Bottom line is, do NOT second guess the engineers that built your car and run a SL/ standard load tire if it requires XL or greater, it could spell trouble on-road and especially off, besides possibly invaldating your factory warranty / insurance if the dealer / adjustor can somehow blame the unsuitable tires for a breakdown, blowout or accident.

Here are a couple of good articles that explain the difference between SL and XL tires, in plain English.

https://www.prioritytire.com/blog/st...load-xl-tires/
Barry's Tire Tech

 

^^^ JLR recommendations copied straight from manual, matches label on drivers side frame... although the label on the car says the cold PSI should be 47/50 (e.g., shows the "normal" pressures from the manual vs light load).

Question -- should these factory fitted tires really be inflated to 47 front / 50 rear? Isn't that crazy high?

 

Suggest you read this thread and the enclosed thread within it for an answer to your question ...

https://landroverforums.com/forum/20...r-l663-104449/

 

Thank you @TrioLRowner