Beware of serious MPG loss with larger tires

[rightmuch]

Several other Mav owners have had the same experience switching tires....One did a detail evaluation and discovered weight, tread pattern , and width were the killers in his lost of 7+- mpg on his Hybrid.

I think the moral of the story is, if you don’t want your mileage to suck, don’t get bigger tires!

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[Bodageta]

Here you go.

Great! Thanks!

 

[rightmuch]

I would venture to say the width was getting ya. The width really adds weight and rolling resistance. A 235/70r17 likely wouldnt have hurt mpg nearly as much also you have to get into the math when calculating a VS scenario. If you arent doing straight test runs, back to back, at top off. Then you will need to calculate distance traveled by tire circumference.

Width was the same. It was the height that got me.

 

[rightmuch]

255 is NOT diameter. 255 is your section width of tread in mm. please look up how tires are. a 225/65r17 is not the same as a 255/65r17 its taller and wider. your speedomter/odometer is off with a 225/65r17. all new cars read 2-3 lower than you are actually going. a 245/65r17 gets the speedometer almost on depending on which brand. as not all brands are identical in size. you might have noticed a whole whopping 1-2 mpg difference if actually calculating with a full to empty tank. you cant calculate off of partial tanks.

255 is height not width

 

[Maverickman74]

Nope. A tire size designation is as follows. 255 represents the millimeters of the tread width, the second number represents the sidewall height of 65% of the first number. Then you add that percentage twice since the diameter of the tire include 2 sidewalls, top and bottom. Then you convert the millimeters of the two sidewalls into inches and add it to the third nimber which is the diameter. So a 255/65r17 is 255mm wide which converts to 10.03 inches. That is your tire tread width. 65% of 10.03 inches is 6.519 inches. The top and bottom sidewall add up to 13.039 inches then you add 17 inches for your rim diameter.

This screwy and confusing system was to punish american for not using the metric system. Truck offroad tires are typically measure in straight inches. You 255/65r17 is equal to 30x10r17. Older tires sizes in the 70s were even more confusing. As in how the hell tall is a G 60? No bloody clue. But the current metric mix sizing system is exactly as I described. It also makes alot of interesting tire sizes. Like 245/70r17 make for a 9.6" wide tire of 30.5" diameter. So slightly taller and slightly narrower than your 255/65r17s.

 

[crgator]

Ok, this chart is based on 70s, not 65s, but it's still interesting. Not only does is show size differences, but also speedo differences.

 

[rightmuch]

Nope. A tire size designation is as follows. 255 represents the millimeters of the tread width, the second number represents the sidewall height of 65% of the first number. Then you add that percentage twice since the diameter of the tire include 2 sidewalls, top and bottom. Then you convert the millimeters of the two sidewalls into inches and add it to the third nimber which is the diameter. So a 255/65r17 is 255mm wide which converts to 10.03 inches. That is your tire tread width. 65% of 10.03 inches is 6.519 inches. The top and bottom sidewall add up to 13.039 inches then you add 17 inches for your rim diameter.

This screwy and confusing system was to punish american for not using the metric system. Truck offroad tires are typically measure in straight inches. You 255/65r17 is equal to 30x10r17. Older tires sizes in the 70s were even more confusing. As in how the hell tall is a G 60? No bloody clue. But the current metric mix sizing system is exactly as I described. It also makes alot of interesting tire sizes. Like 245/70r17 make for a 9.6" wide tire of 30.5" diameter. So slightly taller and slightly wider than your 255/65r17s.

Confusing for sure. I was almost positive the 255 related to height of the tire. At any rate, all I know is, it was too high, too heavy and effed up my mileage.

 

[MakinDoForNow]

How heavy are the new tires? The more weight you have per tire, the more rotational force you're needing to propel the tire, and effectively adding weight to your vehicle as a result. There's also the effect of rolling resistance that will also adversely affect your MPGs. Given that you were using 255s, I'm guessing the rolling resistance was quite high compared to the stock 225 Continentals.

I found online MasterCraft courser quest plus in 255/65/r17 is 30.1" and weighs 41 lbs
And in 225/65/r17 is 28.54" and weighs 33 lbs.

 

[pa-outdoorsman]

I'm sure you lost mileage but I honestly don't buy 7 mpg. Maybe, but I doubt it. As other posters pointed out, changing tire sizes changes the way your truck calculates both speed and distance. Bigger tires make fewer rotations per mile than smaller tires. As a result, the larger the tire, the lower your speed, distance and fuel economy will read. And if you don't account for that difference, then you're not really comparing apples to apples.

I have 245/70/17 tires on my truck, which are three sizes bigger than stock, and I lost only 2 mpg on my Ecoboost.

 

[Baloo]

Do not see you losing 7mpg. When I changedbto a heavier 245/65/17 I only lost a 10th from the stock 225s. I lost about 1 mpg with the lift and about 1 more with spacers. Those are the old math way of doing things. I know I lost wheel horsepower do to the extra rotating mass, but my days of 1320 are long gone.​

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Got 31mpg yesterday on a hour trip.​

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[OneAlienBoi]

Sometimes bigger isn't always better. So much comes into play when things like that are done.

Exactly, a bigger, wider rim/tire combo is going to add a decent amount of weight in the worst possible place. While also increasing rolling resistance dramatically in most cases.

 

[Swamp Donkey]

I would guess that a lot of that mileage difference in a 1500 mile trip was due to it being 99% highway miles as opposed to normal driving around town. I've only drove 600 miles or so in my Maverick so far. Half of that was one trip on the highway, where I got 35 mpg. The other half was driving around locally where I'm getting about 42 mpg.

 

[Lvsparky83]

I run 245/70/17 Toyo’s. I only noticed 3-4 MPG hit witch is totally worth it since it makes the Maverick look great.

 

[KSC Grey Ghost]

Hello All , My Maverick came with those crappy 225 Continentals. After about 1500 miles I sold them and brought a set of 235 Wildpeaks from one of our club in Huntsville Alabama they came off his Maverick lariat . I really love these tires they give me good mileage combination of right at 40 MPG . Or great in the snow and ice this winter no road noise and no hard ride. You're looking for a good set of tires that won't hurt your mileage try the 235 Wildpeaks

 

[Maverickman74]

Confusing for sure. I was almost positive the 255 related to height of the tire. At any rate, all I know is, it was too high, too heavy and effed up my mileage.

You are right its related but not because of its self, but because of the percentage of its self relative to the side wall height. Honestly the whole system was cooked up by tire shop scammers

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