E vs. D Rated Tires

[121x]

Curious if any of the members who are replacing their tires with aftermarket are going with D rated tires with a high enough load rating capacity, to try and improve overall ride comfort? Obviously if you use your vehicle for towing heavy or carrying heavy loads, a D rated tire may not be advisable for safety reasons. However, if you seldom tow or do but are well within the weight limits of a D rated tire, anyone gone that route?

Thanks

 

[1FORDy3rd]

Curious if any of the members who are replacing their tires with aftermarket are going with D rated tires with a high enough load rating capacity, to try and improve overall ride comfort? Obviously if you use your vehicle for towing heavy or carrying heavy loads, a D rated tire may not be advisable for safety reasons. However, if you seldom tow or do but are well within the weight limits of a D rated tire, anyone gone that route?

Thanks

I haven’t yet but will be once these duratracs need replacing which will probably be in the fall.

 

[PapaRaptor]

My 35x 12.50s ended up being "F" rated The main thing is the load capacity. Check the number and the wheels capacity.

 

[Skibum1681]

I personally would never put "D's" on a truck. Regardless of what class it is (150, 250, 350).

I don't direct this at anyone specifically but my biggest pet peeve is when someone buys an HD truck then complains how it rides. These trucks can haul and tow more than ever. The old "lumber wagon" 250's and 350's of the 80's are a fraction of what these trucks are. These trucks are heavy and have tons of power and torque. Tires are not a place to compromise. "D's" are considerably thinner (sidewall and tread) and lighter duty than "E's".

If someone doesn't intend to tow or haul heavy I would first lower the pressure on the "E's" into the 55 PSI range (there is information out there about -your- tires load capacity at various pressures and you should research this first). If that doesn't do it for you, IMHO an aftermarket "softer" suspension is in order. Remember you bought an HD truck, not an F150.

I personally hate how soft and mushy 1/2 ton trucks ride...

 

[BlueKilla]

Match up the load index with your rear axle GAWR - some D range tires will work with the SD and some E range tires won't (especially in the 17" wheel realm).

 

[MT N8IV]

D rated tires generally do not have the weight rating for the HD class pickups and as such not many tire shops will mount them. One thing to keep in mind, D rated tires do not have near the sidewall strength that even an E2 (next class up). The load rating on a D tire is 118 for about 2900 lbs at 50 PSI. The load rating on an E2, which is softer than the E1 Duratracs ours' come with, is 127 and equates to about 3800 lbs at 65 PSI. The E1s jump to an LR of 129 which is about 4000lbs at 80 PSI. As you can see there is an enormous jump from D to an E2 but not much from and E2 to E1.

I currently have E2 tires on my vehicle and air them down to 50PSI in the rear and 55PSI in the front when not towing. The ride is much better while still maintaining the full weight rating for the vehicle. As @BlueKilla noted, there are some D range tires that will work though. You can use a PSI calculator below to figure what PSI you need on what size/class of tire to meet your desired weight rating.

Tire Pressure Calculator

Easy to use tire pressure calculator. Use our tire pressure calculator to calculate the new tire pressure needed when changing tire sizes.

tiresize.com

 

[fubar]

I had D "HD" rated tires to find the balance on my F150 Plat. Worked fine for towing if at max pressure. Just went to E tires and notice a ride difference and ~10% reduction in mileage.

 

[1FORDy3rd]

Match up the load index with your rear axle GAWR - some D range tires will work with the SD and some E range tires won't (especially in the 17" wheel realm).

This is a very good point! What I’ve noticed a lot is most 35x12.50E’s are lower rated than their 37x12.50D’s. I don’t understand the physics of it but it works for me.

 

[Driftwood]

I have F rated on my Tremor. Discount Tire messed up and put 2 E rated tires on my rear, and over filled them to 80 PSI.

 

[Tx-Tremor6.7]

D rated tires generally do not have the weight rating for the HD class pickups and as such not many tire shops will mount them. One thing to keep in mind, D rated tires do not have near the sidewall strength that even an E2 (next class up). The load rating on a D tire is 118 for about 2900 lbs at 50 PSI. The load rating on an E2, which is softer than the E1 Duratracs ours' come with, is 127 and equates to about 3800 lbs at 65 PSI. The E1s jump to an LR of 129 which is about 4000lbs at 80 PSI. As you can see there is an enormous jump from D to an E2 but not much from and E2 to E1.

I currently have E2 tires on my vehicle and air them down to 50PSI in the rear and 55PSI in the front when not towing. The ride is much better while still maintaining the full weight rating for the vehicle. As @BlueKilla noted, there are some D range tires that will work though. You can use a PSI calculator below to figure what PSI you need on what size/class of tire to meet your desired weight rating.

Tire Pressure Calculator

Easy to use tire pressure calculator. Use our tire pressure calculator to calculate the new tire pressure needed when changing tire sizes.

tiresize.com

The D/E ratings are not always the same between different tire manufacturers. For instance, my 37” Nitto Ridge Grapplers are D rated, but they are a 124Q vs the E rated tire in almost the same size are a 121Q. The 37x12.5x17 D rated tires have a max load of 3525 lbs vs 3195 lbs for the 37x13.5x17 E rated. (In any size)

Ridge Grappler Truck Tires

Due to the 335lb max load difference between the D and E, and the extra weight of the E, I went with the higher-capacity, lighter Ds. The max load of the D rated tires x 2 exceeds the GAWR rating of our axles, so I do not feel they are under-rated for a SD or a safety concern as others have commented.

 

[Busa Dave]

I know many people who like to air an 80 psi tire down to 50 psi or even lower however, it will cause issues eventually in the carcass which is the load bearing structure of the tire (even unloaded). What happens is the flex area of the sidewall gets reduced and stress cracks will develop and not necessarily on the outside of the tire where you will see them.

If you want to do this, I would encourage an email to the manufacturer for their recommendation. I have been involved with design, development, testing of many military aircraft tires for our aircraft (34 years) and have covered this subject in finite detail.

FWIW I run 35x13.50-20 Nitto Ridge Runners E rated (also run Bilstein 5100's) and when empty are all 4 kept at 73psi. My truck is the best driving, handling 3/4 I have had. My 2020 Denali was close but on "rough roads" beat me up lol.

 

[Cux211]

I’d stick with at least E’s, F’s if hauling heavy in my experience running D’s on trucks this heavy unloaded you’ll burn those D’s up quick I’ve seen it a thousand times with people wanting to run those 420s

 

[ccw]

I know many people who like to air an 80 psi tire down to 50 psi or even lower however, it will cause issues eventually in the carcass which is the load bearing structure of the tire (even unloaded). What happens is the flex area of the sidewall gets reduced and stress cracks will develop and not necessarily on the outside of the tire where you will see them.

If you want to do this, I would encourage an email to the manufacturer for their recommendation. I have been involved with design, development, testing of many military aircraft tires for our aircraft (34 years) and have covered this subject in finite detail.

FWIW I run 35x13.50-20 Nitto Ridge Runners E rated (also run Bilstein 5100's) and when empty are all 4 kept at 73psi. My truck is the best driving, handling 3/4 I have had. My 2020 Denali was close but on "rough roads" beat me up lol.

I would love more understanding of this. I can't wrap my head around the idea that keeping a tire at or near max inflation pressure when running at half the tire's capacity is better for the tire than lowering the pressure to match the load. Would the sidewall not have the "bulge" (for lack of a better term) it's designed to have? Would the contact patch not be smaller than intended, providing uneven wear?

It's far better to have a tire overinflated for the load than under-inflated for the load, of course, but it seems to me that the ideal (albeit theoretical because of practical reality) scenario would be having your tire pressures constantly changing to match the exact load that's on them.

FWIW, Toyo has published extensive tables for their tires showing what pressures correspond to what capacity:

https://www.toyotires.com/media/3729/application_of_load_inflation_tables_20200723.pdf

Doesn't inherently apply to all manufacturers, but I struggle to see how it wouldn't in principle (even if the exact number might vary).

 

[Cux211]

I would love more understanding of this. I can't wrap my head around the idea that keeping a tire at or near max inflation pressure when running at half the tire's capacity is better for the tire than lowering the pressure to match the load. Would the sidewall not have the "bulge" (for lack of a better term) it's designed to have? Would the contact patch not be smaller than intended, providing uneven wear?

It's far better to have a tire overinflated for the load than under-inflated for the load, of course, but it seems to me that the ideal (albeit theoretical because of practical reality) scenario would be having your tire pressures constantly changing to match the exact load that's on them.

FWIW, Toyo has published extensive tables for their tires showing what pressures correspond to what capacity:

https://www.toyotires.com/media/3729/application_of_load_inflation_tables_20200723.pdf

Doesn't inherently apply to all manufacturers, but I struggle to see how it wouldn't in principle (even if the exact number might vary).

You’re right if I’m reading correctly the whole 80psi thing has to do with liability bs, if you’re not hauling there’s no reason to run 80psi you’ll just burn the centers out of your tires best way to find ideal pressure for unloaded driving is to do a chalk test not sure about fords but over the years I’ve found with a ram 2500 diesel about 60psi gives good even wear on stock tires obviously I’d you go bigger that may change some