Here in France you have 2 competition classes : Sport and Supersport.
Medial Pro insertless tires are compulsory in Sport class.
You have 4 types of compound - Soft - 35° Shore - Medium and Hard.
These tires are rather durable and work pretty well. It is not rare to use them 20-25 packs with good performance.
The only negative point is their weight.
1/Soft tires are used in carpet racing and outdoor fresh temp.
In indoor, we use Tyre treatment like Paragon - Corally TC2 - LRP Grip also.
2/35° Shore have just been released and I didn't have the opportunity to test them yet. That may be a very interesting compound as Sometimes Medium compound are a little bit too hard... and Soft compound may wear too fast.
3/Medium are used for hot temp and Hard are mostly used in Gas racing.
We have the possibility to buy them mounted but I prefer to mount them myself.
I use 26 mm Proline wheels and medium CA, don't use too thin CA, gluing them may be diificult.
Glue them one side then turn-over the tire put some glue on the tire and in the middle of your wheel, turn-over back and take care that your tire is glued equally left and right. Then finish by gluing the other side.
If you still have difficulties to find them in the US, let me know I will try to contact MedialPro for you to find who is the importer in USA.
I will test 35°Shore this week-end race and see how they react with tyres warmer as well. I will let you know.
Best regards from France,