I live in an area with forest roads. I have a gravel/adventure bike that does fine on crushed limestone and packed dirt, but it cannot do deep sand. When I have tried the front tire sinks in and I just about fly over the handlebars. For reference the tires are 700 x 35mm with more of a tread for speed than traction. There is a whole other system of roads that are loose dirt with really deep sand in places (about on the level of sand dunes) that I can't ride with the gravel bike. I'd like to be able to since it would open up more opportunities. I'm contemplating getting a mountain bike (probably hardtail trail or cross country). My question is will this even be enough to get through the sand? If so, is there a tire size that would work? One bike I'm looking at has Schwalbe Racing Ralph Performance 29 x 2.25. Of course, I don't want to invest in mountain bike and find out it can't do the job. I'm hoping someone here with more experience might have an answer.