Tire Load range "E" vs. "D"

BrentR · October 1, 2002

Like a lot of you, I'm thinking about ditching the stock 245's. I want to keep the stock rims, so I've limited my choices to 265/75R16's or 255/85R16's. I can maintain the E rating by staying with the 265's, and I'll need to drop to a D rating with the 255's. Right now, the most I haul is my truck camper (about 2000 lbs) and the occasional trip to the landscape supply company (about 3500 lbs). However I have plans to be towing a 20' ski/fishing boat behind my rig (in addition to the camper) in a couple of years.

Does anyone have real world experience towing/hauling with D and E rated tires? I'm not concerned about exceeding the load capacity. I'm more concerned with stability, especially when considering the taller, skinnier 255's.

Shotgun · October 1, 2002

I took the 245's of of my truck almost immediately,The load range E tires are mostly an overkill and cause your truck to ride rougher.I put the load range D 305-70R-16's on my truck.I tow a 30' RV on a regular basis and believe me it's more than enough tire for the job.Unless you carry over 3000lbs in the back of your truck on a constant basis I recommend the 8 ply load range D.The load range D Wranglers I have on my truck are rated for 2,910 lbs......Gun

CMNTMXR81 · October 1, 2002

All the "D" and "E" ratings affect is the number of ply's in the wall. D = 8, E = 10. Otherwise, more important (at least to me) is the maximum capacity of the tire. For instance, I went from the 245's (load range "E") to 285 BFG's (load range "D"). While I lost a load range, I gained nearly 300lbs in extra load capacity per tire and I get it with 15-20psi LESS than the stock "E" range Firestone's. Like I said, that's more important to me. Some here will say though that they would rather have the "E" range tire cause the sidewall is stiffer and therefore prevents swaying in the sidewall as weight is added.

To those that argue this though, I know I may not tow the heaviest of loads, but I tow cars/trucks all the time and have never experienced this "Sway" due to the "D" range tires and I know my trailer weight weighs more than your boat and I tow at 80+ mph. As a matter of fact, I get compliments on how smooth the ride is both loaded and unloaded.

Shaners · October 1, 2002

I agree that the "D" range tires would be more than enough for what you are doing, assuming you keep them properly inflated for the loads you are carrying/hauling.

My 265/75/16 Michelin Tires are "E" rated and have a higher capacity than the stock 245/75/16 "E" rated Firestones. My tires are probably more than what I need although I do have a 32' travel trailer that weighs over 4 tons and has over 1000 lbs of tounge weight...

Kansas Kid · October 1, 2002

I agree with the others in saying that as long as you maintain (or increase) the maximum load capacity of the tires compared to the stock tires you will be just fine. Like was pointed out you can actually gain some capacity by going to a larger tire (it is able to hold a larger volume of air) but actually go down to a load range D. As far as the sway goes, that will be effected much more by the larger tire then D vs E load range.

I personally prefer the load range E tires if I have a choice. The sidewalls tend to be a bit more durable and they will handle extreme loading better. The load range E tires are also designed to be over inflated by 10psi when at the maximum load capacity combined with high speed driving (highway speeds) to minimize overheating. But for 90% of the people who tow they aren't necessary. The guys that tow at or over the max ratings need them though....

Suburbanite · October 2, 2002

I don't understand how any bumper pull vehicle requires such a high load rated tire. Let's see ... the maximum tongue weight is 1K lbs (AFAIK), D rated tires support at least 2500 lbs EACH, multiply that by 2 & that's 5K lbs (at a minimum)! What am I missing?

Kansas Kid · October 2, 2002

Just a hint, but I seriously doubt the tow vehicle (the one to which the tongue weight is applied) is weightless....

Suburbanite · October 2, 2002

Just a hint, but I seriously doubt the tow vehicle (the one to which the tongue weight is applied) is weightless....

True. But the total weight of the vehicle isn't concentrated on the rear tires. Supposing F/R 60/40 weight distribution on a 6K lb vehicle, that means ~2400 lbs at the rear. Add 1K for tongue weight, that makes ~3400 lbs. Still way under the combined 5K lbs weight rating of the tires in my example.

I think I've figured out what the 'cushion' is for. Didn't consider dynamic (moving) vs static loads placed on the tires. Suspect the 'cushion' provides an extra margin of safety under dynamic loads.

conradv · October 2, 2002

I put the load range D 305-70R-16's on my truck.

Yikes - but that is a SWEET looking unit. And I really like your truck too.

I think that I'll run my stock tires through the winter and suprise myself with new tires next year. :thumb:

DMAX Daddy · October 2, 2002

Later this year Michelin is coming out with LTX M/S 285/75-D 16's that have a higher load rating than the stock 245/75 E series tires (3300 vs 3000) When the 265's I have go bald Ill upgrade to these and put some cheesebag 245's back on the stock rims and buy new rims for the 285's.

LTX/MS Info

http://michelinman.com/assets/pdfs/doc_ltxms.pdf

lovette · October 11, 2002

Shotgun: nice truck. Those are stock rims, right? Did you have to trim anything to get those 305's to fit?

Shotgun · October 14, 2002

Yes they are the factory rims and all i did was trim a little plastic with my pocket knife......Gun

bcfitzsimons · October 14, 2002

Now, the question I have for all you guys is-does increasing the size of your tires matter for tranny shift points? And did you need to get your speedo recalibrated? Fitz

Shaners · October 14, 2002

Now, the question I have for all you guys is-does increasing the size of your tires matter for tranny shift points? And did you need to get your speedo recalibrated? Fitz

Going +1 size (265's) shouldn't cause you to have the speedo recalibrated. Yes it will be off by about 3% but shouldn't cause any problems. At least it didn't for me...

As far as the Ally tranny, I don't know what all can be calibrated on it....

CMNTMXR81 · October 14, 2002

Speedo difference between stock and 265's and 285's.

Stock P245/75-16

Sidewall: 7.234251968503937"

Radius: 15.234251968503937"

Diameter: 30.468503937007874"

Circum: 95.719628134375631"

RPM: 661.933202572123

P265/75-16

Sidewall: 7.824803149606"

Radius: 15.824803149606"

Diameter: 31.64960629921"

Circum: 99.4301706386155"

RPM: 637.231130079072

Speedo difference = 3.876469828143167% too slow

P285/75-16

Sidewall: 8.41535433070"

Radius: 16.41535433070"

Diameter: 32.8307086614"

Circum: 103.14071314285"

RPM: 614.30639821389

Speedo difference = 7.752939656286334%

Hypertech's unit for 8.1's and 6.6's with the Allison DON'T have the ability to adjust for tire sizes. This is because the Allison has it's own controller that no one has cracked yet because Allison won't divulge it's programming. I think Superchips is in the same boat.

Your only option is to see if a dealer can do it, but you are allowed sizes that GM has available for downloads from the tech center for your particular vehicle (it does everything by VIN#). Seeing as though 245's are the biggest, you're most likely S.O.L.

I haven't ajusted mine!