Load Range E1 vs E2

In the "just when I thought I had an understanding of this" column!

Now comes a comparison of E1 vs E2 load range. As I feebly understand Discount Tire's own material, E-rated tires sized 305 and up carry an E-2 load range and a max inflation of 65 psi while E-rated tires sized below 305 carry an E-1 load range and a max inflation of 80 psi. It is apparently entirely possible to run an E-1 or an E-2 tire having the same max load capacity, etc, so the primary (sole?) difference would seem to be overall sidewall stiffness and related handling situations. I admit it's funny to use "handling" and "8,000 lb pickup truck" in the same sentence, but I have to say I've noticed a meaningful improvement in driving/handling when running E1 rated tires at 75-80 psi.

Has anybody run E2s on a truck formerly running E1s and noticed any decline in handling characteristics? I would think the taller tire (305 to 315) running 65 psi max would have to feel squishier than the same tire in a 285 size running 80 psi, with each tire being from the same manufacturer, tread design, and operational application.

Bottom line for me is I'd like a touch more tall (315/75R16) than the size I'm running now (285/75R16) but I don't want to give up sidewall stiffness and "handling". I still chuckle when I write that.....my truck "handles" like a Porsche with 4 flat tires.........and that's on a good day.

Foy

New one on me. But I'm guessing this is the "new" flotation tires in metric sizes. Slowly replacing the old 35x12.50x15 ect.

Never heard of that either.

I wonder if the "new" E2 rating is a marketing ploy for the old standard "D" rated tires with a 65 psi max rating??

Great questions and the same things I asked my tire guy when I went to bigger tires on my GMC 2500HD. What I learned is:

Any truck tire 305mm (11.5") or wider is considered a "flotation" tire and will have a C2, D2 or E2 load range. These tires have a max inflation less than the C, D or E range tires. In the case of the E vs E2 it's 80 vs 65 psi.

Load INDEX is equally important in determining weight capacity as load RANGE. For instance, a load range E, load index 121 tire at 50 psi can carry 2470lbs, whereas a load range E2, load index 121 tire at 50 psi can handle 2755lbs. However, either tire at max pressure, 80 psi and 65 psi respectively, can carry 3195lbs. Very simple, right? BTW - all this info is straight from the Discount Tire document.

With my truck I went from 285/65/18 to 305/60/18 so that I could use flotation tires and air down to lower pressures while still maintaining the weight capacity since I have a FWC on the back and gross weight of about 8700lbs. I've noticed no change in handling but an improvement in ride quality due to the lower tire pressures.

Note that 305 or 315 refers to width, not height. You mention that the 305 or 315 is a taller tire. Only true if you stay with the same aspect ratio (the second number in the tire size). My 305/60/18s are actually a tiny bit shorter than the original 285/65/18s.

Got all that?

Yep, got it, and many thanks for relating your direct, on-point experience.

I am aware that 305-315, etc relates to width. A touch more width is among my goals. The size I'm focused on at present (315/75R16) is within the same aspect ratio as the 285/75R16 I'm currently running. Conversion charts show the 315/75 to be 1.8 " taller and 1.2" wider than the 285/75s, and it's the bump in diameter/height which is my primary goal.

It's particularly great to hear of your experience in the handling and ride comfort departments. I look favorably upon keeping handling "no worse than it is now" when laden while enjoying a somewhat smoother ride.

I am also focused on the load index numbers more than the load range rating.

Good stuff! Thanks!

Foy

It wasn't complicated enough, some lawyer had to make it more so? Yeash!

We went from OEM size 265/something(70?)R16's to GY DuraTrac 315/75R16's to Yoko A/T-S II 315/70R17's on our truck. The 17's are slightly better in the handling dept., but that could also be the different mfg's. Both 315's go down the road at 50 psi. Any higher and they start lifting the tread edges. Both our Polar Moment and our inertia is high, but I'm happy with the handling from either tire.

Foy said:

I am also focused on the load index numbers more than the load range rating.

Click to expand...

Both are important, just depends on how you plan to use your truck. Load range is a rating of the resistance of the sidewall to puncture: E = 10 ply rated, D = 8 ply rated. Actual number and construction of plys are molded into the tire sidewall. So if you go off road ply rating is important.

Load index relates to maximum load. Index number is used because it is used for both Europe, Asia (Kg.) and US (lbf.) max loads.

Didn't know the difference between E1 and E2.

https://en.wikipedia.org/wiki/Tire_code

jim

I've overlooked a rather meaningful detail in all of this: My truck has OEM 7.00 x 16.00 inch wheels. Discount Tire says the narrowest wheel they want to mount a 315/75R16 tire on is 7.5" and they recommend at least an 8" wheel. Dunno if that's policy or a strong recommendation, but I'm ponderin' nonetheless. I'm not particularly interested in buying 4 wheels, but keeping the original wheels and the tires on them and running them parts of each year for the next several years isn't an altogether bad idea. Hmmmm........

Foy

I've been running flotation sizes in C rated for years. The trick to good handling is to have the tread flat on the surface of the pavement. Too narrow a wheel can make the tires feel squirrely and will greatly lessen tread life. if you are going wider go for the recommended wheel width.

Foy if I remember correctly you have a F-250. If I may ask, what was the OEM tire size that came on your truck?
On my new F-350 my OEM tires are 275 mm wide and I am considering upgrading to 295's when these wear out. I feel that these would be the sweet spot for my truck not only due to the approximately one inch wider track but also due the increased payload capacity (4000#'s!).

Since our trucks are so heavy when loaded I would never consider going with a tire that has less capacity than OEM. I have driven my truck on the beaches of the Outer Banks and as you know that is some of the softest sand on the planet so I'm not sure that I need to go significantly wider than OEM.
Just my $0.02..

Squatch and Eddie,

My elderly oil-burner is a single rear wheel F350 Crew Cab diesel longbed, an F250 with a small handful of bells and whistles which allowed FoMoCo to charge a few hundred bucks more for it new in the box.

If I'm not mistaken the OEM rubber was 265/75R16. Dunno for sure since I bought it used with 96,500 miles on the clock. In the nearly 200,000 miles I've racked up on her I've run everything from Nitto Terra Grapplers @ 34 x 11.50 to Michelin LTX M/S in 275/75. She's on Michelin LTX / AT (or some such--I forget the exact letters--they're the AT version of the very popular LTX rubber), in 285/75 size. They've been great tires as were the other set of Michelins I ran for + 50,000 miles. These have 49,000 miles and are still measuring 7/32nds all around. I plugged the drywall screw hole in the right front yesterday and ran it 200 miles to the coast on a hot day today so I suppose it's good for now. I do have some dry-rot sidewall cracks but I don't know how troublesome they may be. The tires have been on the ground for nearly 5.5 years now, since early 2012. Perhaps I'm entering a phase where my truck tires are like my boat trailer tires--you never wear them out because the sidewalls go bad long before the tread wears out.

Entering my mid-60s now and really not in position to drop big bucks on a newer truck and I'm driving the big Ford less and less annually. Pondering a bit bigger rubber to improve the off-road capability somewhat since the downsides of bigger rubber lessen with fewer miles annually. I've never cut a tire and would not consider less than an E and a 10 ply rating. A set of new 8.00 inch wheels is surprisingly affordable if one eschews bling, which I happily eschew. I was already figuring on buying at least one new wheel in order to run with 2 full size spares, so a "4 for the price of 3" deal can be rationalized as "only sinking good money into two more wheels than I was prepared to buy anyway".

Rationalization is great, isn't it?

Foy

Foy-
I like your line of thinking!

I've found that late model take-off wheels can be the lowest cost option, and they're usually rated for more weight than I need to, or should carry. Craigslist is the place for those. These were $250 for 4, but they had usable tires on them and a friend donated the 5th one:


Before these became highly sought after I paid $100 for the 4 of them:


Note that both sets are the 'real' 8 lug bolt pattern, not Ford's "Better Idea". Much more limited in options for the later Fords.

Thom,

I'm not completely familiar with the term "late model take-off wheels" but it seems that may relate to wheels and tires removed from a more or less stock vehicle in order to be replaced with custom wheels and tires. Is that the case and if so, where does one find them if other than Craigslist, etc?

Oh, and the black 'Burban is a dead ringer for my late, great 1990 K1500 Burban. Bought her in 1995 with 80,000 miles as a DD for the wife and as our principal family beach buggy and ski trip transporter. That truck served as a DD for her, both sons, and finally myself over her 15 year career (you know how Dad always gets it as his DD last, after everybody else has gone to something newer and shinier). I might still have her if the President and Congress hadn't decided she was worth $4,500 under the Cash for Clunkers money throwaway in 2009. So she made it to the dealership with something like 190,000 miles on the clock, running on 6 or 7 cylinders, a dead as a doornail battery, bald tires, non-functioning A/C, and the 3rd transmission slipping badly.

Foy

I have not seen tires marked E1 or E2 on the sidewall. The Discount Tire Load Index document defines E2 as wider than 11-1/2".
I just recently upgraded from OEM 265/70R17 to BFG KO2 LT315/70R17E. I have used the Discount Tire document to create a graph to help me find the right pressures for various vehicle configurations (empty highway, empty off-road, camper highway, etc.). I'm also chalking the tires as well.

I also will run a second spare. I bought five of the BFG's then found a forged alloy wheel to match the rest. This will allow me to rotate all 5. The second spare on the steel wheel will be on board for those trips to places far off the beaten path.