I have a 98 4.0 with the AX-15 transmission & recently regeared to 4.88. Am I calculating my crawl ratio correctly at 51? (3.83 first gear x 2.72 transfer case x 4.88 gears)?
Crawl Ratio - Am I doing this correctly?
- Thread starter Andy Maurer
- Start date
Yes, that’s correct. Crawl ratio doesn’t take into effect tire size, which will affect the ultimate speed at which the vehicle travels.
Basically that ratio means your tires will be spinning at the engine RPM divided by that number. So at idle, your wheels would be turning roughly 12 RPM in 1st and 4Low. Multiply that by the tire circumference in feet, and you get the forward speed in feet per second. So a 33 inch tire would result in roughly 107 feet per minute (actually slightly less due to the rolling radius effect).
Basically that ratio means your tires will be spinning at the engine RPM divided by that number. So at idle, your wheels would be turning roughly 12 RPM in 1st and 4Low. Multiply that by the tire circumference in feet, and you get the forward speed in feet per second. So a 33 inch tire would result in roughly 107 feet per minute (actually slightly less due to the rolling radius effect).
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