Going down in tire size

[bigcrazybell]

I currently have 33x10.50x15 on and was thinking about dropping down to 31x10.50x15 on my M1009 because I have a one hour drive to work. My question is will dropping tire size increase my fuel mileage in any way? Thanks

 

[ODFever]

I have 31 x 10.5 x 15 Goodyear Duratracs on my M1009. They are great tires, but are much too aggressive for the truck to be a full-time daily driver. There are a couple of things that could help your fuel mileage. Take my advice and experience for what it's worth. (BTW I've owned my M1009 since November 2006.)
- If your 33's are worn out I suggest buying a set of 31" highway tires. Highway tires will improve your ride and might improve MPG. Aggressive tires have a higher rolling resistance.
- 31" tires weigh less than 33" tires. Less mass = (theoretically) less energy needed to move the beast down the road. I'm no physics expert, but I'm as pragmatic as can be. It's possible that the 31's could make a difference in MPG.
- Accelerate slowly. Let the truck come up to speed. Don't wind out each gear.
- If running on highways or interstates: maintain a speed of 60-65 MPH. Don't go any faster. These trucks are as aerodynamic as concrete blocks. I notice my MPG drops like a stone if I push my M1009 to sustained 70 MPH.

I hope my ramblings make sense, and will help you out in some small way.

 

[cucvrus]

Speaking of rolling resistance. Put a set of LT235/75R15 all seasons on and get away from the 10.5 tread width. Really you don't need the wide tires. I have 4WD pick ups that go fine with tall thin tires on road and off. Not mud bogging or severe off road. But under normal off road use. Snow plowing with the narrow tires. I do know that the stock narrow wheels are out there. They used them on the 1/2 ton 4WD trucks all the way up to 1987 the V10 models. (1987 V = K + C = R) they did away with the C & K for a while and eventually went back to it again. Or NOT. I see newer trucks listed with the K again.

 

[Drock]

Here's a cool RPM calculator ......https://www.ringpinion.com/calculators/Calc_RPM.aspx

 

[Barrman]

Yes, the smaller tires will improve your fuel economy. If you drop your speed down as well. As pointed out above, thinner street tread tires will really help as well.

You didn't state if you need to run a higher speed for your drive or what kind of drive it is. All city and or open road driving where going 58-62 won't get you run over. The smaller tires will be much better.

All highway where you need to have speed. Try 33 x 10.50 tires. Rubber overdrive and less rolling resistance from being thinner.

I went from stock tires max self imposed speed of 62 mph and 22-24 mpg. To 33x12.50 all terrains and haven't seen the high side of 20 since. I do run a lot faster now too though. 65-68 highway.

 

[bigcrazybell]

Most of my driving is on Georgia county back roads and I don't drive over 60. My drive is an hour and I only hit a few lights on the way. I want to go with mud tires since I take it off the road with my fire department when needed and having fun with the kids. Now going to smaller tires how does that affect the odometer?

 

[Barrman]

Stock was 31 x 10.50. So, if that is the size you get the speedometer should be right on. Or, at least as right on as they were back then. Within 3-4 mph.

 

[Skinny]

I'd just run a 31x10.5 Duratrac or AT2 depending on how aggressive you really need and just be done with it. If you are concerned that much with fuel pick up a Civic or Corolla 5 speed beater car. Just my 2 cents...

 

[cucvrus]

I don't drive my CUCV all the time. But when I do I don't concern myself with fuel economy no matter how far I am going.

 

[Zadvark]

View attachment 683938I don't drive my CUCV all the time. But when I do I don't concern myself with fuel economy no matter how far I am going.

And that my friends concludes the conversation. Well said sir, well said.

 

[ssdvc]

32x11.50 and keep them pumped up to 50psi cold. Mileage may vary, but I have seen 22mpg on the highway @ 65mph. Tire pressure is important too, and I like to keep them at least close to the max cold pressure rating on the side of the tires.

Skinny is also good and does work. Some would be surprised at how capable a thinner tire can be, even off road, except in situations where floatation would matter.

 

[Bob H]

Most of my driving is on Georgia county back roads and I don't drive over 60. My drive is an hour and I only hit a few lights on the way. I want to go with mud tires since I take it off the road with my fire department when needed and having fun with the kids. Now going to smaller tires how does that affect the odometer?

If you go with 31's it should make the speedo/odo correct, the 33's would read about 6% lower than actual.

If I ever find the extra money I'm going with 32-11.50 BFG Mud Terrains
Fuel mileage???? aside from the motorcycle my 1009 gets better mileage than anything else I have, lol

 

[scottladdy]

If you go with 31's it should make the speedo/odo correct, the 33's would read about 6% lower than actual.

If I ever find the extra money I'm going with 32-11.50 BFG Mud Terrains
Fuel mileage???? aside from the motorcycle my 1009 gets better mileage than anything else I have, lol
View attachment 684532

I am currently running Mud Terrains on the M1008. They are a very good tire, but unless you are running in the mud a lot I would recommend the All Terrains as there are a lot of compromises with the Mud's. The snow performance is less than I expected. They do growl on the highway. Seems to get worse as they wear, but not as bad as others I have used (e.g. Goodyear Workhorse). Just my .

One thing in favor of the muds. They do look aggressive and draw some attention/compliments.