Wheel Chock Size V Front Wheel Size

I'm looking to buy a wheel chock for my 2005 Speedmaster 865. The wheel chocks I've seen go up to either 19" or maximum 21" front wheels. I'm assuming this is the outside diameter of the tyre they're talking about?

My bike's front wheel is 110/80 -18, however when I measure the outside diameter it's approx. 24" and I've not seen any wheel chocks which go up to this size. Or have I got this wrong and should go off the internal wheel diameter of 18"??

Thanks...

 

@Scoot65 I don't have the answer. I would talk to a dealer perhaps try one out. But I am sure some of the wise ones will be here soon to enlighten us. Perhaps someone with a Speedmaster.

 

I have a wheel chock and it has been used on my Speed Triple, Street Triple, Hayabusa, SV1000 - all with no issue.

 

Thanks for the reply. What sizes are those tyres?

 

A combination of 17 and 18 front wheel sizes

 

130/90/18 CBX
Speed Triple, sv1000 and Hayabusa 120/70/17