Rear End Gear Ratio

What size tires where you running with the 3.42's?

 

Low pro 22.5's, if asking about semi truck.

 

Yes I was. Reason Im asking is Im tring to spec out a new truck. Going from a company driver to o/o. The company truck has 275/80r22.5's and a 10sp and 3.90's I do believe. Im turning 1600 at 65 and test drove a truck the other day that has an 18sp, 3.55's and 11r24.5's. Turned 1600 at 65 in 17th and 1300 in 18th. Problem is with the tall tires the 5th wheel is to tall so thinking 3.42's and 12r22.5's or 3.36's and 275/80r22.5's will get me down to the rpm range I want running unloaded and the 5th wheel height I need to keep our tankers level.

 

Google road speed calculator. You can put in all kinds of combinations.

 

I didn't know they even made a 13 direct. Learn something knew every day I guess.

Did he get a phone call? Don't see why he wouldn't have been able to hang with you by getting his trans out of OD. Sounds like his ECM is programmed different than yours.

 

You lost 300 rpm with one shift on an 18 speed?

 

That's a funny story. @Heavy Hammer @TripleSix

 

Pretty close it looks like.

 

Yep a quick visit to the road ranger site shows .86 and .73 for the two OD ratios. For some reason I thought they were closer together.
http://www.roadranger.com/ecm/group...roadranger/documents/content/rr_trsl-0250.pdf

 

I only lose about 250 RPM on shifts with 18 speed and 2.64 diffs on low pro 22.5 rubber.