Taller tires for pickup?(do they increase mileage?)

[miro]

I don't understand why the ABS / traction control feature would get confused on clean dry pavement i.e. non-winter highway driving. My drive is not a commute so I avoid idiots on the road during rush hours.
For the winter, yes, I'd retain my 15 inch rims and winter tires.

You can see why I still don't have a good answer to my question: Will the MPG improve if I increase the rim and tire size on the rear wheels?
Increasing the size on the front wheels increases weight and frontal area and raises the vehicle.

miro

[CapriRacer]

Originally Posted by miro

I don't understand why the ABS / traction control feature would get confused on clean dry pavement i.e. non-winter highway driving......

I don't understand it either, but there have been enough reports of problems that it shouldn't be discounted. My guess is that the vehicle is measuring ground speed and comparing that to wheel speed. If it sees a difference, the electronics assume the vehicle is skidding.

Originally Posted by miro

......You can see why I still don't have a good answer to my question: Will the MPG improve if I increase the rim and tire size on the rear wheels?....

I'm hoping you realize that there isn't an answer to your question as the issue is complicated and varies all over the lot. There are factors that have much more impact than tire size - and the difference due to tire size isn't consistent.

[miro]

I forgot to add that I have a manual 5 speed transmission.

I really don't care about acceleration and I don't haul heavy loads or pull a trailer. The two-way highway trip is about 450 km and I do it every 2 weeks.
The terrain is not hilly.

Since the rims and tires in the rear are larger, won't the engine RPM be lower for the the same highway speed ( i.e. 100 km per hour - the speed limit) and thus lower the MPG?
miro

[CFECO]

Just a thought, find tires with the highest air pressure rating. I gained over 2 mpg on a 97 Jeep Cherokee by putting on BFG All terrains at 50 psi, compared to the 35 psi old tires.

[t vago]

I'd probably aim for tires that were wider, rather than tires that were taller. That, along with inflating to maximum pressure, will decrease rolling resistance by a lot.

[Frank Lee]

My 2 cents- I have had 265 and 245 tires on my F150 when 235 is stock. They were also somewhat taller. MPG dropped vs stock in both instances. They were all P-series highway tread tires.

[mallrat]

Originally Posted by miro

I don't understand why the ABS / traction control feature would get confused on clean dry pavement i.e. non-winter highway driving. My drive is not a commute so I avoid idiots on the road during rush hours.
For the winter, yes, I'd retain my 15 inch rims and winter tires.

You can see why I still don't have a good answer to my question: Will the MPG improve if I increase the rim and tire size on the rear wheels?
Increasing the size on the front wheels increases weight and frontal area and raises the vehicle.

miro

If the sensors on the front wheels are reading one speed and the sensors on the rear wheels are reading another, that's pretty much the condition the traction control is intended to prevent. ABS will read it as sliding and activate prematurely, decreasing braking performance. YMMV.

I'd go for tall, skinny tires with highway tread. Prolly load range E so I can inflate them to 80 psi for less flex. Check the commercial vehicle tire selection for small delivery trucks, might weigh a little more, but should last longer and have lower RR. Not too much of a disadvantage on long flat stretches of highway.

[CFECO]

Raising the rear will also decrease the slope of the windshield and raise the cab height, possibly increasing drag.

[Joggernot]

Just a thought. 6-ply truck tires are usually rated at 80 psi sidewall. Unless you are in some special location, you'll have to order these tires.

Joggernot

[Big Dave]

I have talked to hundreds of pickup guys and the trend is very clear:

Bigger diameter wheels/tire = worse MPG.

The reason is straightforward. Unless you run very long legs at the same road speed, you have to accelerate. Not only do you have to accelerate the vehicle, you must first accelerate the wheels/tires before they will accelerate the vehicle.

The polar moment of inertia goes up with the square of the diameter, so if you go from 13 inch wheels to 16 inch wheels the polar moment of inertia increases by 33%. The wheel/tire assemblies act like flywheels.

Look at the high-MPG cars available. Small diameter tires. 13 or 14 inch. No 18 inch wheels on the vehicles with high MPG.

Stay with the factory-sized rubber. They do know what they are doing.