What is different about my truck??

[bigtruck94]

235/75r15's are a very good tire size. They were the most common size for a 4wd ranger back in the 90's. Toyo is the way to go if you go little farm working. They are in fact a good all around tire. I see a lot of rangers that have toyo's on them.

 

[ThermonuclearWarrior]

Might seem like a silly question... which toyos? lol

 

[bigtruck94]

The open country A/T 2. Those are actually some decent tires.

 

[ThermonuclearWarrior]

Hmmm.... Ok thanks, I will look into those.

 

[Earl43P]

http://www.dakota-truck.net/CGI-BIN/TireCalc.cgi

Unless you pay Ford to reflash your PCM for the new tire size, you will be going 65mph and indicating about 62. That's a ticket recipe, so keep that in mind, along with the fuel mileage calculations.

In my case, a 5.5% difference. I have to subtract miles (5.5%) when calculating mpg and drive fewer miles than the odometer reports.

Regardless of calculation error, you can expect your mpg to go down with larger tires.


Pasted from the Dakota calculator, your case:

If your speedometer has been calibrated for 225/70 R 15 (27 x 8.86 x 15) tires, replacing them with 235/75 R 15's (28 x 9.25 x 15's) would result in the speedometer reading low by 5.11%.


Same as with the speedometer, if your odometer has been calibrated for 225/70 R 15 (27 x 8.86 x 15) tires, replacing them with 235/75 R 15's (29 x 9.25 x 15's) would result in the odometer reading low by 5.11%.

As far as gearing goes, if you have a 3.73 rearend and 225/70 R 15 tires (27 x 8.86 x 15), changing to 235/75 R 15's (29 x 9.25 x 15's) would be the same as if you kept your current wheels and tires but changed your rearend gears to 3.54's

 

[ThermonuclearWarrior]

It's all off by a little bit then because my winter tires are 5.9% smaller... heh. Well ok then. Will need to get the speedo and odometer re calibrated then I suppose. I think I know someone that can do that. Never occurred to me it would affect the odometer, not sure why I never made the connection, makes sense.

 

[ThermonuclearWarrior]

I take that back... 2.8% different. Not almost 6%!