RPM to road speed calculator vs wheel-size and transmission ratios
When you start altering wheel sizes, final drive ratios and gear ratios, it’s quite easy to make the overall ratios useless. Losing effective use of bottom or top gear is very easy!
Use this little spreadsheet to work out how fast you’re going vs engine RPM, and the;
- Size of your rims and tyres;
- Final drive ratio, and;
- Gear ratios in your gearbox.
As a yardstick, in top gear, 50kph/1000rpm (2000rpm @ 100kph) is cruisy, but 25kph/1000rpm (4000rpm @ 100kph) is fussy.
Feel free to download it to your own machine. Type in the black data, and it calculates the blue info.