275/65r20 MPG

I have looked everywhere and done search after search and cant find an answer.
If I switch to 275/65r20 what will my MPG drop be ( a real # from either a calibrated spedo or hand calculated with GPS). So many people claim a big drop but never changed the spedo or at the same time went to winter gas.

I am also running 3.92 gears and i am looking at terra grappler so weith is about 57lbs per tire/

I did the 275.60.20s and had no mpg difference.. the people probably aren't taking into consideration the diameter change, so realistically they aren't losing any mpg its just calculating based on the old diameters.

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daveray9 said:

I did the 275.60.20s and had no mpg difference.. the people probably aren't taking into consideration the diameter change, so realistically they aren't losing any mpg its just calculating based on the old diameters.

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Click to expand...

So you did what's on there stock....

My RCSB Tradesman, 2014, pentastar, 8 speed, 3.21 gears, came with the aluminum 17" wheels and the 265/70s. At 20,000 miles I swapped them for a set of brand new factory wheels and tires, 275/60r20s in the chrome clad wheel that is optional on the Express trucks.

Paid $600 for the brand new wheels and tires from the local dealer.

Also had the ECU reprogrammed by the dealer for the new tire size.

So far I've noticed a drop in mpgs of about 1-2 overall. However, the tires are still new and it takes a while for new tires to get their best mileage. Last night driving on the freeway the EVIC was claiming 28.2 at 70mph. Before that would have been more like 29.5 at that speed.

Average of 2 mpg lost going to toyo at 275/65/20, which are 61lbs per piece I believe..

However I believe switching to anything that isn't a 4 ply car tires like the stockers are going to make you lose mileage.

winter gas?

The height difference of a 60 to 65 is only like .3 inches...if that. (On 20" rims). Even going 17 to 20's the overall height should be very similar if you get the right sizing on the sidewall to keep everything copestetic.

Enter the new tire size into the ECM and drive.

I'm betting any difference...if any....is negligible.

powderbrad said:

The height difference of a 60 to 65 is only like .3 inches...if that. (On 20" rims). Even going 17 to 20's the overall height should be very similar if you get the right sizing on the sidewall to keep everything copestetic.

Enter the new tire size into the ECM and drive.

I'm betting any difference...if any....is negligible.

Click to expand...

Interesting, so whats the point of going to 65?


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Difference of 60-65 completely depends on the width.

Actually a 275/60 is usually around 33". A 275/65 is usually 34"-34.5". They are the same width.


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powderbrad said:

The height difference of a 60 to 65 is only like .3 inches...if that. (On 20" rims). Even going 17 to 20's the overall height should be very similar if you get the right sizing on the sidewall to keep everything copestetic.

Enter the new tire size into the ECM and drive.

I'm betting any difference...if any....is negligible.

Click to expand...

Not true


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