Video: Can Skinnier Tires Increase Fuel Economy?

[FunkSkunk]

The off-road industry uses a lot of bias-ply tires solely because of their durable nature (fights sharp rocks) and flexibility (better traction when aired down). Interco Tires is one of the best at this esoteric group. Gas mileage is not a priority with an off-road only vehicle. Most of the time these are only wheeled on the trails on the weekends for only 20 or so miles so the impact on gas mileage is not as important as performance.

[chembustion]

Originally Posted by LostCause

I don't know if a thread has been put up on the topic yet, but I know people have recommended them before. I don't remember if it was on GS or here, but someone put extremely skinny tires on their vx. 155/85/13 if I remember correctly.

Ofcourse you lose traction/stopping ability, though. I think a bigger question is what is a better choice: a wider LRR tire or a skinnier normal tire?

Good work, though.

- LostCause

If pressure is a factor ... was the pressure checked / set equal in all tires? This may be one reason the "skinnies" showed better MPG - they're rated at 60 psi. Did they have more than the street tires ?? -CHEM.

[todayican]

I know its been a while but have any of the "temp tire test cars" racked up enough miles to speak to the durability of temp spares over more miles then they were intended for?
Thanks

[Peakster]

The temporary spares did wear quicker than normal tires. The nice thing is that they can be picked up cheap at an auto-wrecker.

[CapriRacer]

I am surprised I haven't posted in this thread - but perhaps it is because it is so old.

Temporary spares (for cars) are designed to a standard with a lower margin of safety than the standard for regular car tires - as are the rims. That's the main reason for the warnings.

Further, temporary spares are manufactured to minimal quality standards - for obvious reasons.

While it it may be hard to believe, wider tires are frequently more efficient. Here's the background on that:

Barry's Tire Tech

Lastly, temporary spares are not designed nor manufactured with any consideration for fuel economy. If fuel economy is the goal, then a better bet would be to use a regular car tire that has been designed for fuel economy.

[MetroMPG]

Yet in this particular thread (Peakster's A-B comparison with donuts vs. regular tires on the rear), he found a fairly large efficiency improvement.

Though not knowing the RR characteristics of the regular tires, it's obviously not something one could extrapolate to every vehicle. And methodology is debatable as always.

[orange4boy]

Hucho has two references to lower CD from narrower tires.

Figure 4.117 on page 281 shows .31 for 195mm tires and .29 for 166mm on the same car

Figure 5.72 on page 295 shows a drop from .32 with 225/55/15 down to .29 for a 155 R 15

Those are some big CD changes.

Shows how GM's Volt Vs Prius CD comparison was set up in the Volt's favour by testing the Prius with 17" wheels instead of the base model's 15"

[Piwoslaw]

Originally Posted by orange4boy

Hucho has two references to lower CD from narrower tires.

Figure 4.117 on page 281 shows .31 for 195mm tires and .29 for 166mm on the same car

Figure 5.72 on page 295 shows a drop from .32 with 225/55/15 down to .29 for a 155 R 15

Those are some big CD changes.

Shows how GM's Volt Vs Prius CD comparison was set up in the Volt's favour by testing the Prius with 17" wheels instead of the base model's 15"

Going from wide to narrow usually means that the tire is not as tall. Could the Cd change have been from the vehicle's body being slightly lower, closer to the ground?

[orange4boy]

In the test results shown for the second reference above, the tire heights are similar. There is a progression of aspect ratios to maintain ride height so the test does isolate the effect of the tire width to CD:

Figure 5.72 on page 295 shows a drop from .32 with 225/55/15 down to .29 for a 155 R 15

The other reference (fig. 4.117) does not specify the aspect ratios.

[naplm00]

I think that most of this has to do with rolling resistance, the skinny the tire and the more air it has in the the smaller the contct patch