tire size/axle ratio RPM calculator needed,

[R72K5]

with 31" tall tires and 4.57 axle and 1:1 ratio final gear in a manual trans what would cruising engine RPM be at 55 and at 65 ?

trying to see if am gonna need taller tires to keep RPM down to where the truc can be driven long ways on freeway continuously without hurting old 350 engine

what do you thnk is safe RPM to stay under for extended periods

thanks

 

[randy88k5]

http://www.dfw-tx4wd.org/gears.html

http://www.angelfire.com/fl/procrastination/rear.html

Good Luck

-Randy

 

[R72K5]

looks like 3221 RPM is what it would be running at 65mph

would that be bad for extended periods of time with an old high mileage 70's 350 ?

thanks

 

[txfiremank5]

Yeah, that's a bit much in my opinion.

I'm going to see if I can post this table directly. If I can, it's for a 1:1 ratio. Higher RPM's for autos, and lower for auto's w/ OD.

 

[R72K5]

Yeah, that's a bit much in my opinion.

I'm going to see if I can post this table directly. If I can, it's for a 1:1 ratio. Higher RPM's for autos, and lower for auto's w/ OD.

yep it shows thanks im saving that one

also manual trans be lower RPM too,- than autos anyways(of identical range ratio)


thanks

 

[sandawgk5]

This is the best RPM calculator I have found and it is pretty darn accurate also.

RPM Calculator

 

[R72K5]

thanks

 

[R72K5]

2700 and 3200 rpm, 55 and 65mpg with the 4.57 and the 31" tires

looks like i need to dump the 4.57 junk and find a 4.10 third member for this eaton axle

or just 14 FF it, 3.73 or 4.10

i cant be running those RPM's with an old 350 like this, it wont last



thanks

 

[txfiremank5]

It, and others can be found here at:

4lo.com

They are on the left side in the menu.

 

[divorced]

Here is a link with a couple calculators I use. It has one for finding a new gear ratio for a tire size change also. http://www.tyres1.com/calculators.html