Gt smoothie 29x2.5 tire

Does anyone use it? Do you know any rolling resistance study about it?

bicyclerollingresistance.com would be the place to look but you may have to be a member to see the details.

The site you mentioned, @JimT, has not tested this tyre.

In terms of weight, actual width and bead it seems to be quite similar to Big Apple 29x2.35. Unless they used a softer rubber (maybe they did though, as one site mentions “extremely tacky rubber”), I’d expect very similar rolling resistance.