Mercedes-Benz Ponton
Tire Size Guide

Terry Morgan / t_zmorgan@msn.com / June 6, 2001



The Mercedes-Benz Ponton shop manual indicates that 190 models came with either 6.40-13 or 6.70-13 tires and says the "effective radius, dynamic" for a 6.70-13 at 60 km/h is 307 mm and at 100 km/h is 313 mm. This is equivalent to a diameter of 24.17" to 24.65." (The 6.40-13 tires are 8 to 6 mm smaller in diameter) This is equivalent to the 185/80-13 size, according to the calculations in the table below.

The width of the tires under both old and new system is the width of the tire: in inches for the old system and millimeters for the new system. I believe the old-system tires had a varying aspect ratio near 80% (?). Under the current system, if there is no aspect ratio given, it is 80 by default; these are slowly becoming extinct.

I measured the circumference of my new 185/80-13s with a tape and I got exactly the same as the calculated circumference. However, there are probably small differences between tire brands. I also measured the section width (widest point of sidewalls) and it corresponds with the width (185 mm).

The "% diff" column shows the difference in circumference from the 185/80-13 size (first row) and indicates the change you will get in engine rpm, odometer, and speedometer readings.

Tire Size Guide

width aspect ratio size diameter circumference % difference revolutions/mile
185 80 13 24.65 77.45 0.00 818.06
175 70 13 22.65 71.14 -8.14 890.6
175 80 13 24.02 75.47 -2.56 839.51
185 70 13 23.20 72.87 -5.91 869.43
195 70 13 23.75 74.61 -3.67 849.25
195 80 13 25.28 79.43 2.56 797.68
205 70 13 24.30 76.34 -1.44 829.99
215 70 13 24.85 78.07 0.80 811.58
195 60 14 23.21 72.92 -5.84 868.84
195 65 14 23.98 75.34 -2.73 841.03
195 70 14 24.75 77.75 0.38 814.94
195 75 14 25.52 80.16 3.50 790.42
205 60 14 23.69 74.41 -3.93 851.51
205 65 14 24.49 76.94 -0.65 823.45
205 70 14 25.30 79.48 2.62 797.18
215 60 14 24.16 75.89 -2.01 834.86
215 65 14 25.00 78.55 1.42 806.60
215 70 14 25.85 81.21 4.85 780.19
195 60 15 24.21 76.07 -1.79 832.96
195 65 15 24.98 78.48 1.33 807.36
195 70 15 25.75 80.89 4.44 783.29
205 60 15 24.69 77.55 0.13 817.02
205 65 15 25.49 80.09 3.40 791.15
205 70 15 26.30 82.62 6.68 766.87
215 60 15 25.16 79.03 2.04 801.68
215 65 15 26.00 81.69 5.48 775.58
215 70 15 26.85 84.35 8.91 751.13

Notes


Created: June 6, 2001 / Jeff Miller
© www.mbzponton.org

Return to the Ponton Workshop page