Tire Question
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Tire Question
I have a 1997 F150 4x4, 4.6L, Lariat. Super Cab 3 door. The stock tires are 255/70/16. Tires need replacing, what size tire can i run that won't effect the gas mileage so terribly much.. Not looking for big monster tires, just want to know if I can go a size or 2 up and not effect the gas mileage or the speedometer....Any suggestions. Dont really use it off road much but I may every once in a while...Not looking for the best brand..but just size options.....
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Joined: Sep 2006
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Not sure about your motives for changing tire size but consider the following;
A larger tire diameter affects the speedometer reading because the speed indication is part of the PCM program that measures and expects a certain result, then sends the results to the speed readout for reasonable accurracy.
Next, while the engine rpm is less for the same road speed with larger diameter tires, the larger tire, depending on brand and tire design, may have higher rolling resistance and negate much of the benifit you expect in mileage from lower engine rpm because however small, you will put more throttle on to maintain speed..
One way to look at it is check the "rolling distance" spec of your existing tire then look for a tire with more passenger car like specs but longer rolling distance to get the best benifit for least rolling resistance.
I know it may be a different way of thinking to some but if you understand the idea and use them within common sense use, it will work as intended as well as running them a bit on the harder side of air pressure.
As an example, when I replaced the stock OEM tires on my super crew with more aggressive tires and for towing capacity, the fuel mileage took a detectable dip.
Good luck.
A larger tire diameter affects the speedometer reading because the speed indication is part of the PCM program that measures and expects a certain result, then sends the results to the speed readout for reasonable accurracy.
Next, while the engine rpm is less for the same road speed with larger diameter tires, the larger tire, depending on brand and tire design, may have higher rolling resistance and negate much of the benifit you expect in mileage from lower engine rpm because however small, you will put more throttle on to maintain speed..
One way to look at it is check the "rolling distance" spec of your existing tire then look for a tire with more passenger car like specs but longer rolling distance to get the best benifit for least rolling resistance.
I know it may be a different way of thinking to some but if you understand the idea and use them within common sense use, it will work as intended as well as running them a bit on the harder side of air pressure.
As an example, when I replaced the stock OEM tires on my super crew with more aggressive tires and for towing capacity, the fuel mileage took a detectable dip.
Good luck.
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Joined: May 2007
Posts: 7
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From: Maine
My 99 also came stock with 255/70/16's. But when I bought it used, it had 265/75/16's on it, so I cant compare fuel economy. I can tell you they do look better compared to other trucks I've seen with the original tires. Also, according to my gps, the speedometer is correct up to about 35 mph. After that it starts to be a little off, but not bad. At 70 on the speedo, the gps says 72-73 mph.
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Brakes, Steering, Suspension, Tires, & Wheels
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