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Old 09-12-2011, 06:25 AM   #15 (permalink)
oil pan 4
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Join Date: Jul 2011
Location: NewMexico (USA)
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Sub - '84 Chevy Diesel Suburban C10
SUV
90 day: 19.5 mpg (US)

camaro - '85 Chevy Camaro Z28

Riot - '03 Kia Rio POS
Team Hyundai
90 day: 30.21 mpg (US)

Bug - '01 VW Beetle GLSturbo
90 day: 26.43 mpg (US)

Sub2500 - '86 GMC Suburban C2500
90 day: 11.95 mpg (US)

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Quote:
Originally Posted by echoRS View Post
Dumb question everyone,
has anyone noted a significant gain in MPG's due to lower cruising RPM's with bigger wheels, in spite of possible losses in aerodynamics and gains in weight?
Very true. On my truck I went from a 235/75/R15 that weighed about 25lb that held 35psi of air to my 31/10.5/R15 that weigh about 40lb and held a max of 50psi of air (I keep about 40 in them) and saw no loss in MPGs. If any thing they went up slightly.
I believe it was due to the better drive ratio and lower rolling resistance from being able to put +5psi in them. (when the truck is loaded I N2 them up to 50psi)
I tested them in combinded city + highway and highway only driving.
The result was unexpected to say the least.
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1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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