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Old 06-23-2013, 07:54 AM   #11
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jdavis,
As mentioned by paulx, you may be in for a rude awakening when you check your mileage running faster. The extra drag from wind resistance and the additional rpms equate to more fuel used. Getting there faster comes at a cost. My rig does 12.8 towing and 17 average (mostly in town) not towing. But it is a diesel. My old gas truck towing a 22' 5er was lucky to get 9 mpg towing over the same terrain. It is all up to you but for the reason of running faster to expect better mileage then it is a bad choice. I did LT tires on the old Dutchmen to get a bit more height and it worked out great. Plus I went with nice chrome wheels that really dressed up the old girl.
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Old 06-23-2013, 01:10 PM   #12
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Going up in speed will NOT increase your mileage. My setup got 10.03 mpg towing mostly at 60 - 62 mph with a short jaunt at 70 on interstate. The same trip home, we were pressed for time and I ran 50% - 60% interstate at 70 and we got 9.2 with less weight as we burned through a weeks worth of wood plus we dropped in elevation coming home from the Adirondacks.
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Old 06-23-2013, 03:55 PM   #13
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The faster your speedo goes the faster your gas gauge goes down
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Old 06-24-2013, 04:18 PM   #14
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What some of you may be forgetting is that going just a tad faster (say 70 instead of 65) and thus putting my RPMs 300-400 higher puts the engine in a better spot along the power band. More torque, more HP. Increased RPM does not necessarily equate to more fuel used.

Larger tires would roll better thus decreasing rolling resistance and increasing the moment of inertia when up to full speed (of course it would take more energy to GET them up to full speed).

Larger tires would also decrease the number of revolutions on the axle, thus decreasing the amount of wear.

And, my whole rig would ride a little more level.

Ultimately the question is, would all the positives outweigh the one big negative of increased wind resistance on the TT at a slightly faster speed?

I don't know. I may not even try and find out. If I do try this, it won't be until next season before our first big trip. I'll need to take the TT to the same place a couple times to do some control runs before (if) I go up in tire size, and then do those runs again to see what happens.
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Old 06-25-2013, 04:34 AM   #15
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I would NEVER run a trailer at 70 MPH. You can get in a lot of trouble very quickly should something happen, either to a vehicle in front of you, or to your rig. Braking power does not increase with increased speed, and controlling a blowout at 70 is much more difficult and dangerous than the same blowout at 55 or 60. To me, the risk to me and my family just isn't worth getting there 15 minutes sooner. JMHO
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Old 06-25-2013, 05:36 AM   #16
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Your theory might work with an aerodynamic, unladen vehicle in ideal conditions but considering the fact that wind resistance increases exonentially with an increase in speed, your theory will not work. Period. Safety concerns aside, you can't get better milege going faster.

Quote:
Originally Posted by jdavis92 View Post
What some of you may be forgetting is that going just a tad faster (say 70 instead of 65) and thus putting my RPMs 300-400 higher puts the engine in a better spot along the power band. More torque, more HP. Increased RPM does not necessarily equate to more fuel used.

Larger tires would roll better thus decreasing rolling resistance and increasing the moment of inertia when up to full speed (of course it would take more energy to GET them up to full speed).

Larger tires would also decrease the number of revolutions on the axle, thus decreasing the amount of wear.

And, my whole rig would ride a little more level.

Ultimately the question is, would all the positives outweigh the one big negative of increased wind resistance on the TT at a slightly faster speed?

I don't know. I may not even try and find out. If I do try this, it won't be until next season before our first big trip. I'll need to take the TT to the same place a couple times to do some control runs before (if) I go up in tire size, and then do those runs again to see what happens.
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Old 06-26-2013, 12:40 PM   #17
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jdavis92--After you increase you tire size don't forget to have you TV's computer reprogramed to suit the tire dia. increase. Larry
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Old 06-26-2013, 12:46 PM   #18
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I'm not sure I follow?

Why would I need to reprogram anything on my TV if I move the TT tires up in size?
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Old 06-27-2013, 09:58 AM   #19
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Jeff,
After further consideration of your statement in post #6 what you need to do is increase engine speed into the "sweet spot" without increasing vehicle speed (and resultant drag). Your truck would need to be refitted with different gear ratio (or smaller diameter tires, not practical) in order to get the engine to turn 3 grand at 60-65 MPH. It may be an expensive proposition and not worth the payback but that is really what you are trying to accomplish by raising the speed of the engine. I went from 3.55 gears on my 96 Ram 1500 to 4.11 gears. It towed better but the gas mileage was not that great either way. Being a 4x4 I had to do 2 sets which cost $1300 in 2002. That's about 325 gallons of gas.
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