Low to Mid-range tubs are becoming harder to find. I'd sat those Challenge Elites are OK but you can get Vittoria Rally for less which have the same TPI
Vittoria Rally are too narrow, they're going on an older bike which won't suit anything smaller than 25mm. Also, all the Challenge tubs I've had have been perfectly round. I've had quite a few Vittoria Rally tubs with bulges.
Low to Mid-range tubs are becoming harder to find. I'd sat those Challenge Elites are OK but you can get Vittoria Rally for less which have the same TPI