6 replies to this topic

[Buchanbull]

changed my mini from 12" to 10" wheels and now id is flat out at 70 mph will I have to change the diff if so what ratio?

[nicklouse]

Err it will not be as the actual wheel size is about the same.  Your Speedo may be reading incorrectly though.

[Spider]

There is usually a very small difference in the rolling diameter between 10's and 12's on a Mini.

Are you getting that speed indication off your speedo or a GPS ?

 

Can you also tell us a bit more about your Mini, what engine size, what's been done to it, final drive ratio (if you know it) etc?

[Quinlan minor]

Mine went from 12"s to 10"s and it made no difference to the top speed.

The comfort, handling and roadholding were, however, massively improved, as were the looks.

Attached Files

•  Mini med small.jpg   56.37K   2 downloads

[bpirie1000]

I used more fuel when i did this.

Probably because it made the car soooo much better and the back roads were calling all the time...

Even once took me 3 hours to get to the local shop for milk... ooops..

Mins are either faster off the line or faster on top end.. canna really have both...

Check the GPS speed..

[Cooperman]

If you do the maths, you will find that the rolling radius of a 165/60 × 12 is not much different from a 165/70 x 10.

I just did the maths and the difference is 0.33 ins on a rolling radius of 9.87" for a 12" and 9.54" for a 10". This is around 3% difference which is about the useable tread depth.

Edited by Cooperman, 15 December 2020 - 10:06 PM.

[Squipper]

Here is some good info

 

 

  165/60-12 165/70-10 Difference Diameter inches (mm) 19.8 (502.8) 19.09 (485) -0.7 (-17.8) -3.5% Width inches (mm) 6.5 (165) 6.5 (165) 0 (0) 0% Circum. inches (mm) 62.19 (1579.59) 59.99 (1523.67) -2.2 (-55.92) -3.5% Sidewall Height inches (mm) 3.9 (99) 4.55 (115.5) 0.65 (16.5) 16.7% Revolutions per mile (km) 1018.83 (633.07) 1056.23 (656.31) 37.39 (23.23) 3.7%

Forum embed code: 

Speedometer Difference Speedo Reading Actual Speed 20 mph (32.19 km/h) 19.29 mph (31.05 km/h) 25 mph (40.23 km/h) 24.11 mph (38.81 km/h) 30 mph (48.28 km/h) 28.94 mph (46.57 km/h) 35 mph (56.33 km/h) 33.76 mph (54.33 km/h) 40 mph (64.37 km/h) 38.58 mph (62.09 km/h) 45 mph (72.42 km/h) 43.41 mph (69.86 km/h) 50 mph (80.47 km/h) 48.23 mph (77.62 km/h) 55 mph (88.51 km/h) 53.05 mph (85.38 km/h) 60 mph (96.56 km/h) 57.88 mph (93.14 km/h) 65 mph (104.61 km/h) 62.7 mph (100.9 km/h) 70 mph (112.65 km/h) 67.52 mph (108.67 km/h) 75 mph (120.7 km/h) 72.34 mph (116.43 km/h) 80 mph (128.75 km/h) 77.17 mph (124.19 km/h) 85 mph (136.79 km/h) 81.99 mph (131.95 km/h) 90 mph (144.84 km/h) 86.81 mph (139.71 km/h) 95 mph (152.89 km/h) 91.64 mph (147.48 km/h) 100 mph (160.93 km/h) 96.46 mph (155.24 km/h)
 

 

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