33 Lego wheels, tires or tracks tested on a wooded board to find the best traction. Presented in order from worst to best. Enjoy!

Test method:
adjust the slope angle until the driving car doesn't slide down or climb up but stays in place
measure the angle of inclination
calculate the coefficient of friction = tan(angle)

Potential sources of error:
traction varies along the wooden board (maybe +/- 1 degree of error in spots)
wheel rotation speed varies (faster rotation adds maybe even 2 degrees to the result with some tires, tried to minimize it by using L-motor with large tires)
vibration (happened noticeable only with 15038c03, those errors were omitted)
weight varies (shouldn't matter in theory)
uneven weight distribution on the 4 wheels
angle measurement inaccuracies
== the results are not very accurate, but I'm confident they are roughly correct

All wheels were wiped clean before testing.

The material of the wood board is pine, untreated
https://www.biltema.fi/rakenta....minen/sailytyshyllyt

Test results:
angle, cof, release year, diameter, part id, link to bricklink.com
13 0.23 1979 -- 3873 https://www.bricklink.com/v2/c....atalog/catalogitem.p
14 0.25 2007 -- 57518 https://www.bricklink.com/v2/c....atalog/catalogitem.p
18 0.32 1977 41 3649 https://www.bricklink.com/v2/c....atalog/catalogitem.p
22 0.40 1977 36 3736 https://www.bricklink.com/v2/c....atalog/catalogitem.p
30 0.58 2006 -- x1681 https://www.bricklink.com/v2/c....atalog/catalogitem.p
30 0.58 1981 64 4266c02 https://www.bricklink.com/v2/c....atalog/catalogitem.p
32 0.62 1975 42 3482c03 https://www.bricklink.com/v2/c....atalog/catalogitem.p
33 0.65 1974 24 3482c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
33 0.65 1986 43 2695c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
34 0.67 2013 -- 57518+14149 https://www.bricklink.com/v2/c....atalog/catalogitem.p
36 0.73 1983 30 4185c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
38 0.78 2016 -- 57518+24375 https://www.bricklink.com/v2/c....atalog/catalogitem.p
40 0.84 2010 14 4265cc01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
45 1.00 2014 95 15038c03 https://www.bricklink.com/v2/c....atalog/catalogitem.p
46 1.04 2016 105 15038c05 https://www.bricklink.com/v2/c....atalog/catalogitem.p
47 1.07 2006 94 44772c02 https://www.bricklink.com/v2/c....atalog/catalogitem.p
48 1.11 2001 103 22969c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
48 1.11 2010 94 88517c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
49 1.15 2007 30 55982c03 https://www.bricklink.com/v2/c....atalog/catalogitem.p
49 1.15 2009 43 56904c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
49 1.15 2011 67 56908c02 https://www.bricklink.com/v2/c....atalog/catalogitem.p
49 1.15 1994 42 6580c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
50 1.19 2006 43 56145c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
50 1.19 2003 43 44292c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
51 1.23 2008 43 56145c04 https://www.bricklink.com/v2/c....atalog/catalogitem.p
51 1.23 2006 55 56145c02 https://www.bricklink.com/v2/c....atalog/catalogitem.p
51 1.23 1991 83 2903c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
52 1.28 2003 70 44772c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
53 1.33 2011 80 56908c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
53 1.33 1990 49 4266c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
54 1.38 2000 56 6595c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
54 1.38 1998 68 32077c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p
54 1.38 1997 63 32020c01 https://www.bricklink.com/v2/c....atalog/catalogitem.p

Music:
Heaven and Hell - Jeremy Blake
https://youtu.be/T9IXodtjRgs

Blue sky video footage:
NoCopyrightVideoHD
https://youtu.be/JmG7iqB-AuA