I've had this truck for 6 years now (it's paid for--woo-hoo!), and the OEM tires are about due to be changed. Factory size is 275/60R20, on 20x9 OEM alloy wheels. Tires weigh 43# each and are 33 inches tall. Wheels, I'm told, weigh 42# each.
I'm considering, when I buy new tires, to get some lighter forged wheels. I realize the FE gain would take me forever to pay back (esp at $300 a piece
), so I'm not expecting massive gains if I pull the trigger. 20x8 Centerlines for my truck (5x5.5 bolt pattern) weigh 28# each. 18x8 Centerlines weigh 22# each, and despite the fact Dodge doesn't put 18s on 1500s, Centerline told me no problem making a set. Replacement tires are the same weight for the 20"; I was thinking I'd get the new Firestone LE2s, which are low rolling resistance. For the 18" wheels, I'd get some 265/70R18s, which are 32.6" tall and weigh maybe 1 pound less.
(Squirrel--see the movie Up!) At $3/gal and $1200 for 4 wheels, I need to save 400 gallons of fuel. A 1 mpg gain would take a long time to pay back... So I did the math anyway. Using a 20mpg baseline, 21mpg as the new mpg, with fuel cost of $3/gallon, it'd take me 168,000 miles to pay for the wheels just in fuel savings. Actually, not totally out of the question as the truck only has 52K right now.
(but that's YEARs of driving for me; we'll probably have flying Deloreans by then)
So with 20s, the truck would lose 14# a wheel, or 64# total. With the 18s, the truck would lose 20# a wheel, or 80# total. The 18 inch tires are also about $30 cheaper each, and the wheels are $20 cheaper each.
I've considered getting taller tires, but it seems the current OEMs are the top of the range, as 275/65R20s weigh no less than 53-61# each, 10# or more than the OEMs. I researched this when I was considering a manual tranny swap, as 6th gear in the (scarcely) available 6-sp manual is .78, and that is nearly 4th gear (.75) in my 545RFE auto (5th is .67). Rear end is 3.55!
I've gone back and forth more times than I care to count, so I'm curious as to your opinions and inputs...
I did look at this thread, but it didn't seem to fully apply to what I'm asking: wheel decision rotating mass vs. aero
Thanks in advance...