Top

Fat-bike Radio – Fat Camp Show #4 – Tire/Wheel Sizes and Tire/Rim Ratios

fat-camp-intro-scott

Above is Scott Quiring’s 29+ Rig

Fat-bike Radio – Fat Camp Show #4

In this episode Ken and Andy talk about Tire/Wheel Sizes and Tire/Rim Ratios. Learn about the hows, whats and whys of using different rim widths with various tire combos.

Show Notes:

Tire rolling resistance links:

“Tech Tuesday – Wider Rims Are Better and Why Tubeless Tires Burp Air” by Richard Cunningham

Traditional 2.25″ MTB Tire

Rim width Inner rim width Tire Casing width Ratio
Mavic 717 22 17 57 3.35
Stans Crest 24.4 21 57 2.71
Stans Flow EX 29.1 25.5 57 2.24
35mm rim 35 30 57 1.90

Racing Ralph 2.4″

Rim width Inner rim width Tire Casing width Ratio
Stans Crest 24.4 21 61 2.90
Stans Flow EX 29.1 25.5 61 2.39
35mm rim 35 30 62 2.07
Velocity Dually 45 39 63 1.62
50mm rim 50 45 66 1.47

Surly Knard 29×3

Rim width Inner rim width Tire Casing width Ratio
Stans Crest 24.4 21 69.6 3.31
Stans Flow EX 29.1 25.5 71 2.78
35mm rim 35 30 72.6 2.42
Velocity Dually 45 39 74 1.90
50mm rim 50 45 75.8 1.68

Tire: 3.8″ Nate

Rim width Inner rim width Tire Casing width Ratio
Clownshoe 105 99 108 1.09
Darryl 82 76 103 1.36
Marge Lite 65 59 95 1.61
Velocity Dually 45 39 90 2.31

4.8 Bud/Lou

Rim width Inner rim width Tire Casing width Ratio
Clownshoe 105 99 119 1.20
Darryl 82 76 113 1.49
Marge Lite 65 59 105 1.78
Velocity Dually 45 39 95 2.44

4 Responses to Fat-bike Radio – Fat Camp Show #4 – Tire/Wheel Sizes and Tire/Rim Ratios

  1. Wade August 8, 2015 at 10:44 am #

    Thankfully, my bikes tires burp from time to time, as opposed to tire farts..O.o

  2. thub August 9, 2015 at 1:20 pm #

    Great show! I’ve listened to all 4 fat camp shows and have learned a lot. Ken does a great job of dumbing down all the lingo and terminology for the laymen. Andy helps in this big time, when the bike geekness gets to deep he reals it back in. Fat shout out to Fat Camp. Greatly appreciate the free continuing education.

  3. Zachary Brown August 10, 2015 at 11:04 am #

    So the lower the ratio the better the rolling resistance?

  4. JR Z August 11, 2015 at 6:45 am #

    Thanks for the reference charts! This is another reason I’ve been adimate in the replies, here, at Fat-Bike.com about posting flat casing widths (in addition to flat tread widths). My calculations show that taking the flat casing width and multiplying by 31% (an odd number, I know) produces the optimized rim width (or, conversely, dividing rim width by 31% produces the optimal tire casing)! The idea is to get the center of the circle produced by the tire in cross-section to, also, be centered on the rim producing the most stable tire averaged across all metrics.