RPM Calculation

[pomai]

RPM calculation

I’m terrible at math, could someone calculate RPM’s for me?

About what should the RPM’s be at 50 mph in 4th gear?
700r4
4.56 gears
33” tires

Thank you very much,
Ed

 

[b454rat]

http://www.4lo.com/calc/gearratio.htm

 

[gone huntin]

Using the calculator in the above link it should be 1625 rpms.

 

[sweetk30]

this one will give rpm's in lots of ranges.

http://www.grimmjeeper.com/gears.html

 

[Greg72]

Using the calculator in the above link it should be 1625 rpms.

plus a couple hundred more if the converter isn't locked up...

 

[4X4HIGH]

plus a couple hundred more if the converter isn't locked up...

Also have to add a few more RPM since tires RARELY measure on size and are usually smaller by almost an inch.

 

[Stomis]

Also have to add a few more RPM since tires RARELY measure on size and are usually smaller by almost an inch.

Yep. Generally when I use a calculator I'll put 35in diameter for 36s, 36in for 37s, etc.

 

[pomai]

Thank you everyone for your help,
Ed

 

[Greg72]

Also have to add a few more RPM since tires RARELY measure on size and are usually smaller by almost an inch.

For an accurate tire diameter, you could always measure the actual "rollout" of the tire. Mark a spot on the tire, then move it forward 10 complete revolutions across the ground. Measure the total distance travelled, divide by 10 and that will give you a highly accurate circumference.

Convert circumference to diameter and plug it into the formula and you should be awfully close to a real life value.

 

[pomai]

For an accurate tire diameter, you could always measure the actual "rollout" of the tire. Mark a spot on the tire, then move it forward 10 complete revolutions across the ground. Measure the total distance travelled, divide by 10 and that will give you a highly accurate circumference.

Convert circumference to diameter and plug it into the formula and you should be awfully close to a real life value.

Thank you,
Ed