Tire Size VS Fuel Economy
#1
Tire Size VS Fuel Economy
I drive my work vehicle a lot - 2002 E-450, 7.3 automatic trans.
Van was bought used with the wrong load rating tires, 225/75-16D, supposed to be E rated tires. Tag on door says van should have '225 /75 E's.
I'm wondeing two things;
1) Did the squishy load rated D tires I have now worn out take a bite out of my fuel milage? Mileage has never ben better than 10.5 mpg driving normally.. I can eek out 11.2 mpg if I drive 50 mph, and keep my foot off the right pedal.
2) What diameter tire makes good fuel mileage with a 7.3 PSD and a 4.10 rear axle ratio? Sems like 225s are a bit small, 245's drop engine rpms by 4%....
Any ideas appreciated.
Bates McLain
www.sprayandclean.com
Van was bought used with the wrong load rating tires, 225/75-16D, supposed to be E rated tires. Tag on door says van should have '225 /75 E's.
I'm wondeing two things;
1) Did the squishy load rated D tires I have now worn out take a bite out of my fuel milage? Mileage has never ben better than 10.5 mpg driving normally.. I can eek out 11.2 mpg if I drive 50 mph, and keep my foot off the right pedal.
2) What diameter tire makes good fuel mileage with a 7.3 PSD and a 4.10 rear axle ratio? Sems like 225s are a bit small, 245's drop engine rpms by 4%....
Any ideas appreciated.
Bates McLain
www.sprayandclean.com
#2
#3
Door placard placed by body manufacturer states 225/75-16 load range E
I'm chasing the fuel issue on this van, 10 mpg really bites my wallet hard, I've met 2 E-450 owners who say they get 13-14 mpg using their trucks similar situations to me.
Motor runs great, just burns a lot of fuel???? Tires wrong size , netting a motor RPM that is faster than needed might be the answer.
I'm chasing the fuel issue on this van, 10 mpg really bites my wallet hard, I've met 2 E-450 owners who say they get 13-14 mpg using their trucks similar situations to me.
Motor runs great, just burns a lot of fuel???? Tires wrong size , netting a motor RPM that is faster than needed might be the answer.
#5
#6
[QUOTE=e-450]I drive my work vehicle a lot - 2002 E-450, 7.3 automatic trans.
Van was bought used with the wrong load rating tires, 225/75-16D, supposed to be E rated tires. Tag on door says van should have '225 /75 E's.
I'm wondeing two things;
1) Did the squishy load rated D tires I have now worn out take a bite out of my fuel milage? Mileage has never ben better than 10.5 mpg driving normally.. I can eek out 11.2 mpg if I drive 50 mph, and keep my foot off the right pedal.
2) What diameter tire makes good fuel mileage with a 7.3 PSD and a 4.10 rear axle ratio? Sems like 225s are a bit small, 245's drop engine rpms by 4%....
Any ideas appreciated.
Bates McLain
www.sprayandclean.com[/QUOTE]
I have an Excursion with 3.73 gears, 315/75R16 (4" lift) tires, and the engine works a little "too" hard, lowering my mileage into the 14-15mpg range .... I have been looking into your question for about 3 months and the general concensious is that 4.10 would be perfect for my setup with the 315's ... should move my rpm's up slightly and mileage back to stock mpg's (16-18) .... We don't have the same rig, but it seems that your question about 225's is accurate .... better hole shot and towing, but the mpg are probably suffering .... 245-265's will probably give you better driving mpgs ... but slightly slow down acceleration when towing ... my $0.02
Van was bought used with the wrong load rating tires, 225/75-16D, supposed to be E rated tires. Tag on door says van should have '225 /75 E's.
I'm wondeing two things;
1) Did the squishy load rated D tires I have now worn out take a bite out of my fuel milage? Mileage has never ben better than 10.5 mpg driving normally.. I can eek out 11.2 mpg if I drive 50 mph, and keep my foot off the right pedal.
2) What diameter tire makes good fuel mileage with a 7.3 PSD and a 4.10 rear axle ratio? Sems like 225s are a bit small, 245's drop engine rpms by 4%....
Any ideas appreciated.
Bates McLain
www.sprayandclean.com[/QUOTE]
I have an Excursion with 3.73 gears, 315/75R16 (4" lift) tires, and the engine works a little "too" hard, lowering my mileage into the 14-15mpg range .... I have been looking into your question for about 3 months and the general concensious is that 4.10 would be perfect for my setup with the 315's ... should move my rpm's up slightly and mileage back to stock mpg's (16-18) .... We don't have the same rig, but it seems that your question about 225's is accurate .... better hole shot and towing, but the mpg are probably suffering .... 245-265's will probably give you better driving mpgs ... but slightly slow down acceleration when towing ... my $0.02
#7
I agree, the tire size needs to get bigger, the reccommended 225s are engineered to have a huge carrying capacity (14#K). I'm looking for the 'sweet spot'
Overall engine rpm to road speed goes up abot 4% from 225's to 245's and from 245's to 265's, each increase drops engine RPMs about 75 prm at a given speed.
My question is what engine RPM is the 'sweet spot' for fuel mileage on a PSD. Most engines are theoretically the most fuel effiecent at the engine RPM where maximum torque is achieved, somewhere around 2600 rpm for us, or at least thats the engineering theory, but real worlsd may be one side of the max torque or another, . My van doesnt have a tach, so I need to figure the rpms using a bit of math... I do know with 225's and a 4.10 my rpms are way past 2600, so I'm ready to make some serious H.P. without downshifting... not a good way to get fuel mileage.
I'm hoping to boost the fuel mileage, lots I like about this work vehicle, I hate buying fuel when I know it should do better. If I could get to 14 (wishful thinking) I could save over $1000 in one year at $3.00 per gallon.
Anyone out there have 4.10 gears and a tach?
Thanks
Overall engine rpm to road speed goes up abot 4% from 225's to 245's and from 245's to 265's, each increase drops engine RPMs about 75 prm at a given speed.
My question is what engine RPM is the 'sweet spot' for fuel mileage on a PSD. Most engines are theoretically the most fuel effiecent at the engine RPM where maximum torque is achieved, somewhere around 2600 rpm for us, or at least thats the engineering theory, but real worlsd may be one side of the max torque or another, . My van doesnt have a tach, so I need to figure the rpms using a bit of math... I do know with 225's and a 4.10 my rpms are way past 2600, so I'm ready to make some serious H.P. without downshifting... not a good way to get fuel mileage.
I'm hoping to boost the fuel mileage, lots I like about this work vehicle, I hate buying fuel when I know it should do better. If I could get to 14 (wishful thinking) I could save over $1000 in one year at $3.00 per gallon.
Anyone out there have 4.10 gears and a tach?
Thanks
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#8
Welcome to FTE. The sweet -spot for mileage is 2000 rpm or just under about 60 to 62 mph with 4:10s in my dually with stock size 235/85/16 tires. I average 14.5 to 15 local driving not alot of stop and go but some and I have a heavy foot. I would think about adding a tach to your van I know if I keep the engine below 2 grand on every shift it helps mpg. I believe its harder to do with an auto like my dad has (2002 F250 cc 2x4 ) he keeps it below 2grand every shift by watching the tach and gets great mileage.
#9
Bates, you can also look at your engine to try to increase mpg. Make sure all your boots are good and not leaking. Try tighting the clamps to see if you may have a boost leak. Also look at your up-pipes, if you see any soot on the connections, you have a leak. Change fuel filter and oil.
Good luck.
Good luck.
#10
OK, thats the needed information, Thanks for the real numbers Dave.
Your tires are a full 2 inches taller than my 225/75's, and they would drop the rpm's about 170 rpm. I dont know the OD ratio for my tranny, so the real number drop exludes me. One more number to find to crunch numbers.
In reality, it takes 'X' amount of HP to push a vehicle down the road, I cant do uch about resistance to wind, but if I can get the motor to run at a more fuel efficent rpm range, I will do what I can do. Hell, the truck has a 5 speed, If I need to pass or go up a hill, I'll drop to 4th.
About time to find some new 'skins'. Maybe the combination of taller tires (lower rpm's) and a stiffer load range E will net out with some fuel savings.
Thanks
Your tires are a full 2 inches taller than my 225/75's, and they would drop the rpm's about 170 rpm. I dont know the OD ratio for my tranny, so the real number drop exludes me. One more number to find to crunch numbers.
In reality, it takes 'X' amount of HP to push a vehicle down the road, I cant do uch about resistance to wind, but if I can get the motor to run at a more fuel efficent rpm range, I will do what I can do. Hell, the truck has a 5 speed, If I need to pass or go up a hill, I'll drop to 4th.
About time to find some new 'skins'. Maybe the combination of taller tires (lower rpm's) and a stiffer load range E will net out with some fuel savings.
Thanks
#12
definitely 4.10 rear. Thats why the speced' tire size was '225/75'.
Tire/ratio combination is for a reason, 14,000 GVW.
Great for hauling a big load, which I don't. I could easily have gotten by wieght -wise with a E-350 which has a 10,000 GVW, but with the E-450 you get bigger brakes and a real transmission.
Big question now is how tall a tire (based on engine rpm) should I go with.
Tire/ratio combination is for a reason, 14,000 GVW.
Great for hauling a big load, which I don't. I could easily have gotten by wieght -wise with a E-350 which has a 10,000 GVW, but with the E-450 you get bigger brakes and a real transmission.
Big question now is how tall a tire (based on engine rpm) should I go with.
#14
#15
Ray,
mine is a cube, its pushing some air up top, but even so, it should do better than 10mpg... at least thats what I hear from other owners with very evry similar trucks.
I talked to a guy in the Wal-Mart parking lot who had a truck exactly like mine, who said with a load of used books (book dealer) he got 14 mpg, and when he pulled his 24 foot travel trailer (!!!) he got 12 mpg.
What fuel mileage range do you usually get?
mine is a cube, its pushing some air up top, but even so, it should do better than 10mpg... at least thats what I hear from other owners with very evry similar trucks.
I talked to a guy in the Wal-Mart parking lot who had a truck exactly like mine, who said with a load of used books (book dealer) he got 14 mpg, and when he pulled his 24 foot travel trailer (!!!) he got 12 mpg.
What fuel mileage range do you usually get?