I cut these sleeves from a new piece of 10" DR 17 HDPE pipe from WL Plastics. The inner diameter is 9.5" which works great for smaller tires like the ones that come stock on the Coleman DT200 and Scooter X drift trikes.

Inner Diameter
Inner Circumference
Wall Thickness
Outer Diameter
Sleeve Width
Weight
Hardness
Text		 9.486"
29.801"
0.632"
10.75"
5"
59 Ounces Each
60 Shore D
40 FT IPS 10" DR 17 WL Plastics SD PE4710 PE 445574C PC/PSI 125

The most accurate way to measure a tire is by circumference. Wrap a fabric measuring tape (typically used for sewing) around the outside of the tire. Measure the tire twice, deflated and inflated. For example, the 10" Duro tires measure 29.25" deflated and 31.5" inflated. The inner circumference of these corresponding sleeves is 29.801" which is in between the two tire measurements (deflated & inflated).

Wider sleeves are more slippery.
Skinny sleeves are more sticky.
Square 90º edges are better for racing and cornering.
Round edges are better for drifting and 360s.
PVC is harder and more slippery.
HDPE is softer and more sticky.

Sparky Sleeves are hand made by Scott Blake in Saint Paul, Minnesota.