Falken AT3W LT 275/60 r20 mpg decrease

[MaineRam19]

I just installed Falken 275 / 60 R AT3W on my I 2019 Limited (3.21 etorque) and I have seen a substantial decrease in gas mileage going from 21 to 17.5 mpg on the highway traveling at 68-69 via GPS not my speedometer. Speedo is off by approx 1 mph. I am trying to determine if this decrease in mpg more of a result of the increase tire size going from a 31.9 inch tire to a 33 inch tire or a result of the increased tire weight, approximately 41 pounds stock to 58 pounds in the Falken. Thoughts?

 

[ferraiolo1]

All of the above.


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[BowersFJ]

Both …. Could have gone P instead of LT in that size


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[Snofire]

Everything you posted would cause this to happen. Takes more muscle to move more weight and keep it in motion.

 

[Whoa_Ram]

Try adjusting your speedometer and let your truck get use to them. I think once you do that you will be able to tell how bad it actually is.

 

[mikeru82]

Your speedometer error depends on the speed you are traveling. At 30 mph you're actually going 31 mph. But when your speedo reads 60 you're actually going 62.1 mph. Larger tires require fewer revolutions per mile (obviously). Your new tires turn 20 revolutions per mile less than stock, or about 3% fewer. This will definitely affect the perceived fuel economy in a negative way. Add to that the heavier tires, and possibly slightly higher stance. I think you'll find that your fuel economy isn't is bad as you think if you correct your speedometer/odometer error. But the heavier tires are probably the biggest factor in your decreased fuel economy.

 

[MaineRam19]

Try adjusting your speedometer and let your truck get use to them. I think once you do that you will be able to tell how bad it actually is.

I just performed a fill up and the calculated mpg is 18.1 not taking into account that my trip odometer is not a bit off. Is anybody running the P/standard load Falkens 275/60r20 and can provide some examples of MPG’s?
Also, I had an alignment performed when they install the tires and I noticed the truck seems wants to wander in the lane more than stock. My Lane keep assist does not like this even with setterings turned down. Running 52 psi as Falken technician recommended.

 

[Whoa_Ram]

I feel like your PSI is a little high but that’s just my thought. I don’t think you need that much unless you are carry weight in your bed. When I changed out my tires to 275/60’s but only weighs 43 pounds my MPG’s were reading around 16-17 as well. Once I changed my speedometer and got use to the tires I got back up to the 20’s again. Not always that high but better then the 16-17 I was seeing.

 

[MaineRam19]

I feel like your PSI is a little high but that’s just my thought. I don’t think you need that much unless you are carry weight in your bed. When I changed out my tires to 275/60’s but only weighs 43 pounds my MPG’s were reading around 16-17 as well. Once I changed my speedometer and got use to the tires I got back up to the 20’s again. Not always that high but better then the 16-17 I was seeing.

Thank you. What did you use to change your speedometer? Does this void the manufacturer warranty?

 

[Whoa_Ram]

I used AlfaOBD as I had a few things I wanted to change at the same time.

 

[Idahoktm]

You'll gain back about 1 mpg once you program your speedometer, but the biggest hit to your mpg's is the weight of those tires. The last time I bought LT tires, I lost about 3 mpg and the tires were the same size as stock. The tires I bought for my 2021 Laramie are 33's, but they are XL's and only weigh 49lbs which is about 3lbs heavier than the stock tires.

 

[SpeedyV]

I feel like your PSI is a little high but that’s just my thought. I don’t think you need that much unless you are carry weight in your bed. When I changed out my tires to 275/60’s but only weighs 43 pounds my MPG’s were reading around 16-17 as well. Once I changed my speedometer and got use to the tires I got back up to the 20’s again. Not always that high but better then the 16-17 I was seeing.

If they’re LTs, that’s not super high. I used to run around at 55 unloaded on E-rated tires (80 psi rear if pulling heavy).

But I’ve not run D-rated tires, so I’m curious as to whether they feel the same.

 

[Scram1500]

Another factor is the knobby tread pattern that increases rolling resitance

 

[Finn5033]

Yep weight and rolling resistance.

 

[Falken QA]

I just performed a fill up and the calculated mpg is 18.1 not taking into account that my trip odometer is not a bit off. Is anybody running the P/standard load Falkens 275/60r20 and can provide some examples of MPG’s?
Also, I had an alignment performed when they install the tires and I noticed the truck seems wants to wander in the lane more than stock. My Lane keep assist does not like this even with setterings turned down. Running 52 psi as Falken technician recommended.

What was the factory tire size and tire pressure? I'll double check this adjusted air pressure as techs will provided a air pressure to match the same load capacity of the factory tires.

 

[c3k]

Well, OP, I went from factory Falken Wildpeak AT3Ws at 275/55r20 and loved them, but increased to an AT3W in 275/65r20.

32 inch stock to 34 inch.

My mileage (ecodiesel) took a bigger hit: 28 to 23. (Highway, easy throttle.) I expected some drop, but not this big. Live and learn...

 

[MaineRam19]

What was the factory tire size and tire pressure? I'll double check this adjusted air pressure as techs will provided a air pressure to match the same load capacity of the factory tires.

275/55r20 - 36psi is factory

 

[Falken QA]

275/55r20 - 36psi is factory

looks like Ram equipped the 1500s with a 275/55R20 113 LR tire (different from a P275/55R20. As such, at 36 PSI supports 2535 lbs per tire. By moving into a LT275/60R20 (D range) tire, the light truck inflation chart would match that load capacity per tire at 52 PSI. The air pressure is adjusted only to match

The wandering can be due to the higher tread depth of the new tire (along with extra inch increase in OD), compared to the shorter tread depth of the non LT 275/55. Of course, if this does not sit well with you, the AT3w you have does have a 30 day/1000 mile trial period on it, so there is no obligation to stay with the tire. Simply return back to your seller to exercise this.

 

[MaineRam19]

looks like Ram equipped the 1500s with a 275/55R20 113 LR tire (different from a P275/55R20. As such, at 36 PSI supports 2535 lbs per tire. By moving into a LT275/60R20 (D range) tire, the light truck inflation chart would match that load capacity per tire at 52 PSI. The air pressure is adjusted only to match

The wandering can be due to the higher tread depth of the new tire (along with extra inch increase in OD), compared to the shorter tread depth of the non LT 275/55. Of course, if this does not sit well with you, the AT3w you have does have a 30 day/1000 mile trial period on it, so there is no obligation to stay with the tire. Simply return back to your seller to exercise this.

Thank you for this information.

 

[SD Rebel]

As mentioned, everything you stated has played a role, but the biggest is the diameter of the tire and the type of tire it is. Larger tire and higher rolling resistance of the tread will both play a big roll in your lower mpg.

1/2 " increase usually results in a 1-2 mpg loss. So going a full 1" in diameter and losing 3.5 mpg is about right.