I looked into the WTB TBs and some are actually using them on the front of normal 27.5 bikes on regular MTB rims. So, if you really don't want them, I'd take them and if they don't work, I'll pass them on to the next guy who's dreaming of PLUS, but isn't ready to buy one yet. If you line up the sale of your son's Trek with Ben, you can give them to him and he'll give them to me at work.Thanks!