Upgrades and Aftermarket - 6.0L EngineUpgrading and adding aftermarket equipment to your 2003-Up Super Duty or Excursion with 6.0L Power Stroke diesel engine. Please confine discussion of topics in this forum to those items that are specific to the 6.0L Power Stroke engine.
I put on Toyo 35x12.50x17 M/T's and a 2.5" lift, and suffered. I lost 1.5 mpg city and 2.0 mpg highway. Others say they get great mileage with lift and bigger tires, but I don't see how. I drive pretty easy, and mileage is not good. I get around 13.6/15.0 consistently, used to get 15.0/17.5 with the stock 265/70/R17's.
I always thought that I would put bigger tires on my truck when I got it. But I only wanted 35s or something like that, and maybe a 4" rancho lift.
Would adding these things really hurt my fuel mileage much?
Yes. A 4" will drop you about a solid 3m/g. Going higher will cause more loss.
Its physics at work. By lifting the truck you're doing two things that adversely affect economy. 1 - you're increasing the frontal area, which makes it that much harder to push down the road. 2 - you're increasing drag by allowing more air to flow under the truck where all that drag inducing stuff hangs out into the air stream.
The largest tires I'd consider would be 285's, and even these will increase rolling resistance at low speeds.
OMC
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Feb 03 6.0 Silver F-250 SD SC XLT long box, 6-spd 3.73ls, Fx4, Stock, Spray-in liner, Contico box.HARPOONED.
I agree w/ OMC.I have 285s on my truck and haven't lost any mileage but I would go any bigger,just personal preferance.But I'm sure the bigger you go the worse it is.
Truck in sig, 15mpg highway unloaded, 12ish around town. Towing depends on the load. I've had as low as 9 and as high as 11.5. I don't know what it got before I put the lift and tires on. It has just over 15K on it right now.
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07 CC LB FX4 TS 6.0 Oxford White, 4.5" DR lift, 315/70/17 BFG on 17x8 American Racing Mojave
i have a 6" lift and 37's and i got around 11-12 and i drive city and highway. Thats hand calculated not the in accurate mpg meeter in the truck. I recently added a 4" cat back i can tell a 15-20% gain which is good. But its totally worth the mpg loss to have my truck lifted i love it. Just do it
Yes... it will seriously hurt your mpg, and power. I run a 4" lift with 35x12.5x16r Goodyear wrangler tires and get 11mpg average with mostly highway. Programmer always set on extreme and a heavy foot doesnt help tho! Anyway, larger tires are sweet, but have their drawbacks. I believe you lose about 2.5% of your horsepower and torque for every inch your tires are larger than stock. However, the coolness factor is priceless haha !!
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2003 F-250 XLT FX4 6.0l turbo diesel, sc shortbox, torqushift 5spd auto.
Procomp 4" lift, 315-75-16R Goodyear Wrangler tires on 16x10 American Eagle Wheels, Edge Evolution tuner, Airaid intake, Magnaflow performance 4" tubo back dual exhaust with 5" tips, WARN Premium manual locking hubs, Bushwacker fender flares, Smoked cab and 3rd brake light, Aftermarket headlights, tail lights and reverse lights, TomTom GO 920 Navigation system, Ford custom seat covers, Lund tonneau cover.
you lose about 2.5% of your horsepower and torque for every inch your tires are larger than stock. However, the coolness factor is priceless haha !!
Just to clarify, the maximum power and torque of the engine doesn't change due to the tire size. The larger tires will have a greater mass moment of inertia, which makes it harder to get them spinning. They will most likely have a larger contact patch and thus more rolling resistance. They will also most likely be wider than the stock tires, have more aggressive tread, and stick out farther than the stock tires, causing more aerodynamic drag. And, since they are taller, the distance from the pavement to the center of the wheel is greater, resulting in less force pushing the vehicle forward. With all of these things added up, you will need to use more of the engines available power and torque to maintain the same vehicle speed and acceleration as before. I hope that wasn't too nerdy of a respons....
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07 CC LB FX4 TS 6.0 Oxford White, 4.5" DR lift, 315/70/17 BFG on 17x8 American Racing Mojave
Just to clarify, the maximum power and torque of the engine doesn't change due to the tire size. The larger tires will have a greater mass moment of inertia, which makes it harder to get them spinning. They will most likely have a larger contact patch and thus more rolling resistance. They will also most likely be wider than the stock tires, have more aggressive tread, and stick out farther than the stock tires, causing more aerodynamic drag. And, since they are taller, the distance from the pavement to the center of the wheel is greater, resulting in less force pushing the vehicle forward. With all of these things added up, you will need to use more of the engines available power and torque to maintain the same vehicle speed and acceleration as before. I hope that wasn't too nerdy of a respons....
Yes, you are correct. By "losing hp and torque", I did not mean your engine hp will drop, but the felt force at the point where the wheels contact the pavement will be less due to greater lever arm. I meant that the hp and torque will be "wasted" in a sense (without going into Newton's laws and all that crap). That is what actually matters with respect to the force pushing your vehicle forward. Drag, resistance of the tires, and inertia of the wheels are also factors that increase the amount of power required to get the same acceleration as a similar truck with smaller tires and no lift. Anyway, as said before :Yes, larger tires and a lift will significantly impact your mpg.
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2003 F-250 XLT FX4 6.0l turbo diesel, sc shortbox, torqushift 5spd auto.
Procomp 4" lift, 315-75-16R Goodyear Wrangler tires on 16x10 American Eagle Wheels, Edge Evolution tuner, Airaid intake, Magnaflow performance 4" tubo back dual exhaust with 5" tips, WARN Premium manual locking hubs, Bushwacker fender flares, Smoked cab and 3rd brake light, Aftermarket headlights, tail lights and reverse lights, TomTom GO 920 Navigation system, Ford custom seat covers, Lund tonneau cover.
Last edited by NBhunter80 : 07-11-2008 at 10:34 AM.
While I didn't go with a lift (tires fit without one) I did switch to 305/70R18 (35x12x18) tires and honestly didn't notice any drop in either power or fuel economy.
At some point in the future I am looking at putting a 2.5" leveling kit up front as well as 3" drop hangers in the rear (need to keep my load capacity) so I guess I will have to see what happens then.
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Steve Urban
Semper Fi!
2007 F350, Lariat High Line, SRW, SC, LB, 4x4, 6.0/auto, FX4, Camper Pkg, HD alt, Red w/custom black two-tone, Buckstop bumpers F&R, Warn 16.5ti winch, Line-X, F550 coils, 305/70R18 ProComp XtremeMTs
2007 Apex9.5 truck camper
1973 Bronco (stock), wife's
1973 Bronco (HEAVILY modified), mine
2006 Mustang V6, Screaming Yellow, wife's
2006 F350, Amarillo, SRW, CC, 4x4, SB, 6.0/auto (traded)
2004 F350, SRW, CC, SB, Sport, 4x4, 6.0/auto (bought back by Ford)
Lift and tires make mpg suffer,however you can mitigate that somewhat by chanigng gears.
I run 4.30 gears with 8 in lift & 37 toyo's. Driving normal, empty hwy = 16.2, city 13.8. Towinng heavy 10-11. towing light 12-13.
Hay Idaho Slim, OT but you are running 40's with "just" a 8" lift? does it rub alot? or at all? how you like it? I want to go to 40's on my truck from the 37's I'm running now but I dont want to go to a 10" lift.
03 F250 6.0L PSD ,TORQSHIFT,CC,SB,FX4,LARIAT
Linear Mode
