Al33 Rims and inflated tire widths

Here are some measured inflated tire widths on Al33 rims, which we use in our RFSW3 wheels. The inner width of the rim is 19.6mm, which puts it in line with many of the current popular wider rims. There aren't a lot of surprises on this list, and with these data points it's possible to interpolate/extrapolate most of the other tires out there.

All tires inflated to 95psi prior to measurement. Format is tire make & model / size / inflated width:

Continental GP4000sII / 23 / 25.65

Continental GP4000sII / 25 / 28.60

Specialized S-Works Turbo / 24 / 25.40

Specialized S-Works Turbo / 26 / 27.15

Maxxis Padrone TL / 25 / 26.50

Michelin Pro4 SC / 23 / 24.5

Again, no huge surprises. Every tire is somewhat bigger than stated size, and GP4000s considerably so. With an outside brake track width of 25 and an overal widest width of 26.2, the rims themselves shouldn't cause fit issues with any frames we know of. 

We have helped to arrange a wind tunnel test for Al33 and a bunch of other comparably relevant wheels on 2/9. We will post the information from that as soon thereafter as possible. I can assure you that we're as curious about that as you are. 

Following that test, we'll make the order pages live. 

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My GP4000sII at 105 PSI measured 29.8

Michael Kruse

Will these also be available as Select/Select+ (disc and non-disc) builds as well?


Good data point, thanks, and the exact reason why we provide this information. A lot of frames aren't able to take tires that are 27 or 28mm in dimension, no matter what it may say on the side of the tire.


You might have an issue with frames with bracket mounted front derailleurs or possibly clearance through the brake calipers. I was unable to use a 25 mm Schwalbe Pro One with the newer Pacenti SL23 rim due to clearance issue on my Cannondale Six-13 with 7800 Dura Ace brakes and a bracket mount 7800 FD.

Katherine Snell

The width on those 25mm 4000s II are ridiculous! They're going to make my Synapse ride like a flippin Lazy Boy.


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