towing, stock tires vs 33 inch tires
07-07-2008, 09:48 AM
#1
Senior Member
Thread Starter
towing, stock tires vs 33 inch tires
ok, i have a 2006 supercrew with the 5.4l 4x4 3.55gears. and i was towing aproximately 6000 to 6500 lbs for about 120 miles. i got about 8.5 mpg. my last truck was a 97 f150 with the 4.6l 4x4 and 3.55gears and towed about 6k for same distance and got 11 mpg. that had stock tires on it. so my question is, did going from a stock 17 inch wheel with 255/70 tires to a 20 inch wheel with 33 inch tires cause a big difference in mpg when towing? should i change back to stock wheels when going on this trip?
07-07-2008, 02:06 PM
#3
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the answer is yes, when towing put your stock tires on. those 20s are really heavy and you lose lots of horses with those wheels. i wish i never went with 20s. im getting an average of 9 miles to the gallon.
01-28-2009, 04:52 PM
#6
Senior Member
Can't argue with your results, but wouldn't have expected that much of a drop - looks to be in the neighborhood of 20% - ouch!
Assuming the truck is in good tune, with no fault codes present.
Was your '97 a SuperCrew also? Looking for any significant differences between the trucks in terms of weight.
Is there a difference in the ride heights between the trucks? Air passing under the vehicle produces significant additional drag - part of the reason for ground effects packages and air dams.
Using one of my favorite websites - http://www.miata.net/garage/tirecalc.html - looks to be only a 6% difference in tire height. If you didn't correct your speedometer, then your true mileage should be closer to 9, for what it's worth. Also, you would be going 6% faster than actual, which would ping your fuel economy comparison a bit, but certainly no where near getting it back up to 11.
Rolling resistance of tires is another consideration - however, I don't know how to quantify this in terms of mileage and brands.
On the other hand - 120 miles at 11mpg would call for 10.9 gallons, at 8.5mpg - 14.1 gallons. A difference of 3.2 gallons, perhaps in the neighborhood of $6 - not worth the effort of changing the tires out to me, unless this was a daily trip.
Assuming the truck is in good tune, with no fault codes present.
Was your '97 a SuperCrew also? Looking for any significant differences between the trucks in terms of weight.
Is there a difference in the ride heights between the trucks? Air passing under the vehicle produces significant additional drag - part of the reason for ground effects packages and air dams.
Using one of my favorite websites - http://www.miata.net/garage/tirecalc.html - looks to be only a 6% difference in tire height. If you didn't correct your speedometer, then your true mileage should be closer to 9, for what it's worth. Also, you would be going 6% faster than actual, which would ping your fuel economy comparison a bit, but certainly no where near getting it back up to 11.
Rolling resistance of tires is another consideration - however, I don't know how to quantify this in terms of mileage and brands.
On the other hand - 120 miles at 11mpg would call for 10.9 gallons, at 8.5mpg - 14.1 gallons. A difference of 3.2 gallons, perhaps in the neighborhood of $6 - not worth the effort of changing the tires out to me, unless this was a daily trip.
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01-28-2009, 10:09 PM
#8
Bleeds FORD Blue
Can't argue with your results, but wouldn't have expected that much of a drop - looks to be in the neighborhood of 20% - ouch!
Assuming the truck is in good tune, with no fault codes present.
Was your '97 a SuperCrew also? Looking for any significant differences between the trucks in terms of weight.
Is there a difference in the ride heights between the trucks? Air passing under the vehicle produces significant additional drag - part of the reason for ground effects packages and air dams.
Using one of my favorite websites - http://www.miata.net/garage/tirecalc.html - looks to be only a 6% difference in tire height. If you didn't correct your speedometer, then your true mileage should be closer to 9, for what it's worth. Also, you would be going 6% faster than actual, which would ping your fuel economy comparison a bit, but certainly no where near getting it back up to 11.
Rolling resistance of tires is another consideration - however, I don't know how to quantify this in terms of mileage and brands.
On the other hand - 120 miles at 11mpg would call for 10.9 gallons, at 8.5mpg - 14.1 gallons. A difference of 3.2 gallons, perhaps in the neighborhood of $6 - not worth the effort of changing the tires out to me, unless this was a daily trip.
Assuming the truck is in good tune, with no fault codes present.
Was your '97 a SuperCrew also? Looking for any significant differences between the trucks in terms of weight.
Is there a difference in the ride heights between the trucks? Air passing under the vehicle produces significant additional drag - part of the reason for ground effects packages and air dams.
Using one of my favorite websites - http://www.miata.net/garage/tirecalc.html - looks to be only a 6% difference in tire height. If you didn't correct your speedometer, then your true mileage should be closer to 9, for what it's worth. Also, you would be going 6% faster than actual, which would ping your fuel economy comparison a bit, but certainly no where near getting it back up to 11.
Rolling resistance of tires is another consideration - however, I don't know how to quantify this in terms of mileage and brands.
On the other hand - 120 miles at 11mpg would call for 10.9 gallons, at 8.5mpg - 14.1 gallons. A difference of 3.2 gallons, perhaps in the neighborhood of $6 - not worth the effort of changing the tires out to me, unless this was a daily trip.