Dan Masters of Alcoa, Tennessee has developed a neat tool to calculate and graph road speed vs. engine speed data.  The tool (which I call Calculator) is designed to allow one to adjust the tire size, gearbox ratios and rear end gear ratio to match a specific vehicle. Calculator is a Microsoft  Excel Workbook.  

An example of Calculator data  with TR6 specifications is included here.   Click here to view the Calculator.   Click on the tabs on the bottom of the Calculator to shift between the chart and graphs.  If you wish to print the Calculator example data be sure to use page or printer setup to set to landscape output format and set printer to print all linked documents.  Use  BACK button on browser to return to this page. 

Click here to download the Calculator  Microsoft  Excel Workbook.

Dan has written an excellent electrical repair manual for the  TR250/6.  I understand another is in the works for the TR4.   Info on the TR250/TR6 manual is available at:  Dan can be contacted at: