What rpm at 65mph ???

I have been reading many posts but still need help.
I am looking to buy a 2016 kw t680 mx13 500hp, 18 spd manual, with 3.7 rear ratio.
I am trying to find out what rpm it will turn at 65mph ,??
I pull a dry van with 20-30k lbs.

 

Sorry 11R22.5 tires

 

Why would you want those specs if your not running heavy haul?
Those are horrible specs no fuel mileage there.

 

That's what I'm trying to figure out !!! The tractor is a great deal... I'm trying to find out if it is worth the fight.

 

Roughly 1410rpm. Google road speed calculator.

 

Thank you 062.
Well at 1410 rpm, why would the fuel mileage be so poor ?
Isn't this an ideal rpm ??
And should be good on hills.

 

First off what engine? Detroits like 1500 rpm. Cats like 1200 rpm. Unknown for Cummins

 

I never had any experience with the mx motors. @Long FLD runs one.

 

At 65 you will be on the upper end of where you want to run the engine. The torque curve on the MX is low (1100-1400 rpm). If your plan is to consistently run 60 to 65 then it won’t be bad.

 

Mx13 500hp.
I think that it is 2nd or 3rd gen.
I currently own a 2013 Peterbilt 587 mx13 455hp, 13spd automatic, 3.42 ratio, 22.5 tires. I run 1300rpm at 65 mph but... it doesn't like hills or to much weight.

 

Here is the formula.
11r22.5=42 inch diam.
11r24.5=44 inch diam. (These can be plus or minus a 1/4 inch by manufacturer and tire model )
18 speed eaton top two gears.
17th gear =.86
18th gear =.73