OktsCamp
Alberta, Canada
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Joined: 05/22/2006
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I have a 2007 Chev 2500HD CC 4x4 Duramax that came with the factory LT245/70R16 tires. My dealer happens to have a set of the new body style 2500HD "optional" tires/rims from a truck they put a lift kit/larger tires on. Now, they are willing to let me have them for a steal of a price, but should I be concered as they are LT265/70R17's. One side of me is saying no...because they are an optional item on the new body style 2500HD's, but the other side of me is thinking of potential impact on my TV's mileage and speedo readings etc. They are a greater load capacity which is nice as well..plus I like the new style rims. Any thoughts.
thanks
OktsCamp (aka Mike)
07 Chev Silverado 2500HD LT CC, SB, LBZ Duramax/Allison 6 Speed
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donn0128
Pronounced Ore-gun
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I went from the anemic LT245's to LT265's. Did not notice any thing except maybe a more accurate speedometer. You will be a bit more sluggish off the line too. Down side, when it comes time for new tires, it will probably cost you more.
Donn
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goodcruisin
Greenwood, IN
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It's not that simple. Wider tires create more rolling resistance. More agressive tread works against aerodynamics. A heavier tire/rim combination will lower fuel economy. The raised chassis will increase drag. My neighbor has a 2003 1500 4x4 with a 5.3L. He put a 3" lift on it. Went from 245 to 305 tires (9.6"x30.5" vs. 12"x34"). His mileage went from 18 to 13 mpg.
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Kenneth
Washington, the state
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The LT265/70R17 tires have an outside diameter that is about 3-1/2% bigger than the actual original LT245/75R16 tires. Don't worry about the difference.
As John says, the wider tread will cause a bit more fuel consumption due to higher rolling resistance. John's neighbor didn't really have that much gas mileage hit...with the bigger diameter tires his odometer isn't logging all the miles he's running, so the gas mileage, while worse, isn't quite that bad. The bigger tires also hurt gas mileage if they cause the transmission to downshift more often that it would with the stock tires.
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Jumbo Cranium
Texas where else
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Actually when I went from stock 245/75/17's to 285/70/17's. my mileage INCREASED by almost 10 percent, 2 mpg. My truck has a 3.73 rear end. But the Dodge 6 speed manual is very low geared even in 6th. The extra weight is pretty much a non factor. 1 or 2 hundred pounds here or there has almost zero effect on mileage. Do you get worse gas mileage when your wife is in the truck with you? Not enough to tell.
Right after the switch I drove past one of those radar gun trailers on the highway. With my old tires at 55 on my speedo, the radar gun showed 53. With the new tires it shows 58 when my speedo says 55. So running the same rpm I'm traveling almost 10 percent faster. That means better mileage. I had plenty of power to spare since my whole rig weighs less than 14k.
I think the increase in final drive ratio way more than offests a tiny bit of weight and an even tinier bit of rolling resistance and an almost infinitesimal amount of increased drag caused by the wider tires.
Kenneth is right about the truck not logging all the miles so my increase is probably not as great as it seemed at first. I'll have to check against a known distance someday. I know its 24 miles exactly to work, I could run to work for a week and check the mileage then and see how it compares to the old tires.
Roger
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goodcruisin
Greenwood, IN
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Kenneth wrote:The LT265/70R17 tires have an outside diameter that is about 3-1/2% bigger than the actual original LT245/75R16 tires. Don't worry about the difference.
As John says, the wider tread will cause a bit more fuel consumption due to higher rolling resistance. John's neighbor didn't really have that much gas mileage hit...with the bigger diameter tires his odometer isn't logging all the miles he's running, so the gas mileage, while worse, isn't quite that bad. The bigger tires also hurt gas mileage if they cause the transmission to downshift more often that it would with the stock tires.
That mileage was correct. I failed to mention that he used a programmer to recalibrate the speedo.
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8.1 Van
Millstone NJ
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Quote:Actually when I went from stock 245/75/17's to 285/70/17's. my mileage INCREASED by almost 10 percent
E rated LT285/70R17's are hard to find and Tire Rack does not have them. LT235/85R16E Rib tires like the Michelin XPS would give the best mileage in vehicles that could use 16" wheels and don't need more than 3,042 lb capacity each.
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SoCalDesertRider
SanDiego, CA, USA
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Jumbo Cranium wrote:...the Dodge 6 speed manual is very low geared even in 6th.... 6th gear is overdrive in that transmission. You're probly refering to the axle gearing...
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Jumbo Cranium
Texas where else
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8.1 Van wrote:Quote:Actually when I went from stock 245/75/17's to 285/70/17's. my mileage INCREASED by almost 10 percent
E rated LT285/70R17's are hard to find and Tire Rack does not have them. LT235/85R16E Rib tires like the Michelin XPS would give the best mileage in vehicles that could use 16" wheels and don't need more than 3,042 lb capacity each.
These are D-rated but have a higher load carrying capacity than my E-rated tires did. The handling and ride did not suffer at all.
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Jumbo Cranium
Texas where else
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SoCalDesertRider wrote:Jumbo Cranium wrote:...the Dodge 6 speed manual is very low geared even in 6th.... 6th gear is overdrive in that transmission. You're probly refering to the axle gearing...
Yes I know 6th is overdrive. it still a very low gear for overdrive. I have 3.73 rearend and in 6th gear at 70 mph the rpms were over 2200. Ask anyone that actually owns a Dodge with this tranny and they will tell you they wish it had another gear. With the taller tires the rpms are a right at 2000.
What I was referring to was correct.
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