How to figure road speed.

[Jones]

Got an engine that'll govern out around 2,800 RPM, top gear is one to one and the axle ratio is 6.44(?) Tires are 53" tall. Is there a simple formula I can use to get a ballpark idea of my top speed in the baby HEMTT when I get it on the road?

 

[cranetruck]

(2,800)(60)/(381)(6.44)(1)=68.5MPH

revs/mile=(5280)(12)/(53)(3.14)=381

Your gear ratio for the standard Rockwell axles is 6.72, which would give you a top speed of 65.6 mph.

The revs/mile can be found along with other info from tire spec sheets and may be dependent on air pressure tire design etc.

Also, check max speed rating for your particular tire, off-road tires are not rated very high.

Hoping this helps,

 

[98hd]

http://www.4lo.com/4LoCalc.htm

 

[73m819]

98hd--- thank you for the caculator

 

[cranetruck]

So much for the oldfashioned way...

 

[73m819]

98HDs link needs to be moved to the tec. section so it is not lost

 

[98hd]

98hd--- thank you for the caculator

No problem. I saved that to my favorites along time ago, and use it all the time.

 

[Jones]

Hey thanks guys. Am trying to figure out, when the baby HEMTT is operational, if I'll be able to keep up with traffic or if I'll have built the world's fastest roadblock.

 

[Wick246]

It won't matter - everyone in front of you will slow down to 20 to stare at the rear view mirror.

 

[Jones]

Yeah, thought about that. And while I appreciate Bjorn's admonishment about considering max tire speed rating I think my pucker factor will increase exponentially, so as to render the tire rating a non-consideration. I'll be the one doing 42 mph and screaming like a woman.