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wjohn · 08-01-2014, 10:21 PM

CapriRacer, thanks for that explanation. I did not know about the derating factor of 1.1 for trucks. Looks like if I go with these tires, I'll definitely want the 109T/XL version since the de-rated load capacity of the 105T/SL tires is right at my 3650 GAWR. I also see that Dodge only specs XL tires for the 235/75R15 size in the owner's manual, and my door spec plate matches that.

I won't have 2,000 pounds in the bed of this thing at all times (like, say, if I were to have a utility bed full of tools or something) but it will definitely see that amount of weight now and then.

With the tire pressure, the spec plate does call out the old standard of 35 PSI front and rear. The manual says to add 3 PSI for high speed driving. I guess my experience with the older Hondas has led me to somewhat ignore the manufacturer's spec - for both my Civic sedan and hatch the pressure spec was 32 PSI front and rear. It's glaringly obvious that this was done for ride quality, as the fuel economy and the handling both noticeably improve with air pressure at 38 PSI or so. The sedan especially handles like a completely different car at higher pressure. I will run 38 PSI in this truck but may not go much above that as I doubt it'll help the handling of the Dakota as it does with the Civics.

The old Michelin LTX A/Ts that are currently on the truck were at 50 PSI when I got it (minus the leaking front left on the smashed up rim). I just went and checked and they are actual LT tires, though.

So, I think I don't need the max PSI rating of the 109T/XL Grabbers, but I do need the load capacity. Plus they should still be better than the LT version of the Grabbers and hopefully better than the Michelins for fuel economy.

08-01-2014, 10:21 PM	#16 (permalink)
wjohn EcoModding Lurker Join Date: Apr 2014 Location: KS Posts: 15 Hatchback - '90 Honda Civic DX 90 day: 44.98 mpg (US) GTS - '90 Dodge Dakota 4WD Base 90 day: 18.04 mpg (US) Topless Brick - '66 MG MGB Roadster 90 day: 27.19 mpg (US) Sedan - '91 Honda Civic DX 90 day: 40.27 mpg (US) Thanks: 1 Thanked 4 Times in 4 Posts	CapriRacer, thanks for that explanation. I did not know about the derating factor of 1.1 for trucks. Looks like if I go with these tires, I'll definitely want the 109T/XL version since the de-rated load capacity of the 105T/SL tires is right at my 3650 GAWR. I also see that Dodge only specs XL tires for the 235/75R15 size in the owner's manual, and my door spec plate matches that. I won't have 2,000 pounds in the bed of this thing at all times (like, say, if I were to have a utility bed full of tools or something) but it will definitely see that amount of weight now and then. With the tire pressure, the spec plate does call out the old standard of 35 PSI front and rear. The manual says to add 3 PSI for high speed driving. I guess my experience with the older Hondas has led me to somewhat ignore the manufacturer's spec - for both my Civic sedan and hatch the pressure spec was 32 PSI front and rear. It's glaringly obvious that this was done for ride quality, as the fuel economy and the handling both noticeably improve with air pressure at 38 PSI or so. The sedan especially handles like a completely different car at higher pressure. I will run 38 PSI in this truck but may not go much above that as I doubt it'll help the handling of the Dakota as it does with the Civics. The old Michelin LTX A/Ts that are currently on the truck were at 50 PSI when I got it (minus the leaking front left on the smashed up rim). I just went and checked and they are actual LT tires, though. So, I think I don't need the max PSI rating of the 109T/XL Grabbers, but I do need the load capacity. Plus they should still be better than the LT version of the Grabbers and hopefully better than the Michelins for fuel economy.