D rated Tires

[brods]

Dodge Warlock, take all the internet experts with a grain of salt. Your posts are fine and are preferred over posts from individuals who show no tolerance of others opinions and feel their unsupported opinions are fact. Your experiences with tires, added to the experiences of others, help make a clearer picture. Do not stop posting because of an intolerant few.



One can look at tire spec charts and see some interesting things (when the data is available). Looking at Toyo’s charts and comparing the same size tires which come in both D and E ranges, one will see some sizes have no differences other than max load and max inflation pressures. There are others where the E range tire is heavier, indicating something is different in the construction.



In any event the point you’ve made is a good one, that a D rated tire lowers your maximum safe inflation pressure. Considering the only way we can influence the handling of a tire is by adjusting the inflation pressure, it follows that E range tires will give one a larger range of tuneability compared to D range tires.

 

[Vaughn MacKenzie]

Well here's a little twist for you guys to throw into this thread. . . a guy at my church has a '96 2wd longbed club cab with 17" Goodyear GT II tires (275/60/17). I checked the sidewalls, Load Range C . . . 2337 lbs weight rating

I rode with him a couple months ago when towing his 26' 5th wheel. Amazingly there was no wallowing or soft sidewalls, good & stable through the curves. They have worn well, they're down to about 20% tread, but man what a scary thought.

Vaughn

 

[betterthanstock]

Read it. I assume you were refering to the Toyo info that says to run whatever additional pressure necessary to meet required load capacity without exceeding the rated pressure of the new tire. It also states quite clearly in bold red print to never use less than the oem recommended tire pressure. Our 01 shows 65/80. That means that a fully inflated D-rate at 65psi is the bare minimum for the front and only an E-rate at 80psi will qualify on the back.

Well, you see, a 315 (BFG) tire at 50 max PSI has identical load to the OEM 265 size at 80 max PSI. That is due to the much larger footprint of a 315, compared to a 265. Ultimately, a tire will be crushed by a load until the footprint equals the weight divided by the inflation pressure.





At 2500 lb (per tire) one inflated at 50 psi will have a footprint of 50 square inches, and one inflated to 80 psi will have a footprint of 31 square inches (regardless of tire size).





Yes, a lower pressure tire will bend more in corners, but its loss of traction is more gradual (less sudden) than that of a higher pressure tire. I don't know if anyone has documented the safety of softer vs harder tires.

The Explorer fiasco is due to people driving at too low a pressure for that tire size, which causes the tire to flex excessively, and blow up from overheating.



A tire rated and certified to carry 3200 lb at 50 psi, will do so just as safely as one rated to carry 3200 lb at 80 psi when both are properly inflated.



For comparison, a Hummer H2 (6700 lb) on 315 bfg tires stops 60-0 in 151 ft, and turns at 0. 64g.

A 3500 dually dodge on 235 tires (7100 lb) stopss 60-0 in 160 ft and turns 0. 62 g (Motor trend).

 

[DHuffman]

I am not trying to mislead anyone. I read the information and it does support you technically. Legally it is pretty hard to misunderstand the bold red print that said to never run lower than the oem recomended pressure. It also said to cut (divide) the rated weight load of the oversize tires by 1. 1. If you offer up evidence it must be able to withstand discussion.

I try to refrain from posting my opinion. If you read the info carefully, you will understand the calculations you need to be able to interchange tires without injecting personal opinion - these are tables developed by the manuafacturer. The dividing by 1. 1 rule is FOR USING P METRIC tires on light trucks - NOT LT tires.



Replacement tires must be of a size, load range, and load capacity (by inflation) that are capable of supporting the load of the vehicle's originally installed (O. E. ) tires.

 

[JDiepstra]

Well here is my . 02. I ran the 285/17/70 BFG AT KO's all winter with 9'2" of V-plow and plow mount out front, totaling about 1000 extra pounds, with no problems. At 65 PSI. A bigger tire can hold more at less PSI.

 

[Shanley]

when I bought my truck new in 05, the new toyo E 35-12. 50 17's were back ordered so I had the dealer put the BFG mt's on. I was leary about the load rating since I'm a bricklayer and constantly haul heavy loads. On the weekends I pull a 26' toy hauler. After 2 1/2 years ans 62,000 miles I bought another set of BFG's, the new km2. So far after 11,000 miles I like these just as well.