Fuel Mileage Adjustment?

Hey!

I have a 2014 TRD Sport 4x4 automatic. I got it lifted 3" last year and finally just this past weekend got new tires and wheels. I upgraded to 18s and went with 275/70/18 tires. I used to have 265/70/17. I am wanting to know what my "average" fuel economy adjustment may look like? Though I am also wondering if getting my exhaust upgraded to a flow master messed with it as well. When I first got the truck stock, it was getting about 18-18.5 mpg. After getting the flow master it went to about 17. I would have thought the flow master would have made my fuel economy better, no? Thanks for advice!

 

The exhaust system installed on our trucks from the factory have been tuned specifically with the proper amount of back pressure for the engine. I am not sure of the exact science behind it, but freeing up the exhaust leads to less low end torque and worse gas mileage. The only benefit is the increased volume

 

Decades of engineering and innovation went into providing the best performance and aftermarket mods are deceptively robbing your wallet with false claims of better performance.

 

If you're looking to figure out how much your speedometer is off (and hence your odometer and trip meters and MPG) see below
https://www.tacomaworld.com/tirecalc

 

Is there any good aftermarket exhaust besides the stock muffler? I just didn't like how quiet it was...

 

The exhaust is not hurting your mpg, it's the lift and larger tires. Your speedometer is off compared to the old size which also makes it look like you're getting even worse mileage. You're around a 4-4.5% difference in tire size which makes your speedometer read lower and the miles traveled will read lower than they actually are. The lift and tires create more resistance which is where you're losing the mpg, I would leave the exhaust alone, it's not causing any problems.

 

@JL8Jeff Yeah, the new tire is about 1.5" taller than the tire that was on it. I will be calling Toyota to see if they can recalibrate the computer to match the new tire size. I got the flow master exhaust installed last summer. Are you saying my mpg is probably not as bad as I think since it is off?

 

Trd exhaust.

 

Toyota won’t do it. As there isn’t a way to recalibrate it with factory components.

 

And yes take the old tire size and new tire size put them in a tire comparison chart and see the percentage difference between the two and there ya have the percentage your off in mpg and mph.

 

@gotoman1969 Is the TRD exhaust a specific exhaust or is that another word for factory muffler? I had Dodge do it on my old truck. Do you have to have a tuner instead to match?

 

It’s a Toyota exhaust. It’s has a nice tone to it and really has no drone at highway speeds.

 

@gotoman1969 I will take a look at it. Looks like a spendier exhaust that includes piping and not just a muffler. I just spent money on my wheels and tires so have to wait anyways Right now I am focusing on getting the speedometer and everything matched to my tires, if I can. I know people have said take it to the dealer to recalibrate and others have said a tuner. So looking at options.

 

Yes it’s a complete one piece cat back exhaust.

 

I would suggest running past a speed trap to see what reading it shows vs what your speedometer shows to see if it's really off by much. You're probably looking at 2-3 mph around 55 to 60 so it's not too big of a deal. My truck is dead on with bigger tires but I don't know if the previous owner did anything to correct it or not. I think Toyota knows most people will go bigger with tires and calibrate it high to begin with.

 

Thanks @JL8Jeff. It's off about that much. 3-4 ish. I spoke with Toyota though and they can recalibrate so I'll look into the price