Axle Ratio/Tire Size Calulator 1.1

Here are a few calculators that may be useful in deciding tire size, gear ratios, and other stuff.

These calculators created by Mark Medina - http://www.4lo.com/




Top Speedo Gear Ratio Crawl Ratio MPH_RPM P-Metric tire size



RTI Ramp Index at 4lo.com









Top Speedo Gear Ratio Crawl Ratio MPH_RPM P-Metric tire size

RTI Ramp Index at 4lo.com

Ever wonder how far off your speedometer is with your new bigger tires? I'm using a simple ratio calculation, so this info will only approximate your corrected speed and depends on the accuracy of tire size diameters (assumimg nothing but tire size has changed).

Speedo converter
Original Tire Diameter:
New Tire Diameter:
Speedometer Reading (MPH): Corrected Speed (MPH):









Top Speedo Gear Ratio Crawl Ratio MPH_RPM P-Metric tire size

RTI Ramp Index at 4lo.com

Ideal gear ratio CHART at 4lo.com

Now that you have your truck lifted, you want bigger meats. They look cool and have the potential of being very functional, but they may also be robbing you of power/gas mileage. This calculator will get you back to a Gear Ratio that's closer to your original. Enter the values on the left and press Compute.

Find new Gear Ratio with new tire size
New Tire Diameter:
Old Tire Diameter:
Current Gear Ratio: New Gear Ratio:










Top Speedo Gear Ratio Crawl Ratio MPH_RPM P-Metric tire size

RTI Ramp Index at 4lo.com

Ever wonder what your low-low-low gear ratio is, your "crawl ratio"? You'll need to do a little research by finding out the transfer case and transmission ratios first. Enter your values on the left side, press Compute and your answer will be on the right.

Find Overall Crawl Ratio
Transmis Ratio:TransCase Ratio:Axle Ratio: Overall Ratio:










Top Speedo Gear Ratio Crawl Ratio MPH_RPM P-Metric tire size

RTI Ramp Index at 4lo.com

I've spend a bunch of time trying to WAG (wild ass guess) my actual MPH when going down the road. By knowing your gear ratios and tire size you'll get a more accurate idea here. Enter the value on the left, press Compute.

Find MPH
RPM: Tire Diameter:
Axle Ratio:Transmis Ratio:TransCas Ratio:
MPH:

I suppose if you don't have a tachometer you could use this form. Otherwise it's useful to find out what your RPMs will be after you change gears and /or tire size. Enter the values on the left, press Compute.

Find RPM
MPH:Axle Ratio:Transmis Ratio:
TransCas Ratio: Tire Diameter:
RPM:







Top Speedo Gear Ratio Crawl Ratio MPH_RPM P-Metric tire size

RTI Ramp Index at 4lo.com

This formula is a nice way to get the tire diameter of those P-metric tires that are common on just about everything stock. For example a 265/75R16 would be around 31.6 inches tall. Enter the numbers into this form in the order you read them from the tire and press Compute.

Convert P-Metric tire to Tire Diameter inches
Example: 195/75R15
/ R
Tire Diameter:


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