You don't need a dish tool. The truing stand is fine as someone mentioned if you chech one side. Also you can check the dish with two equal blocks of wood on each side of the rim. Set the rim flat on a flat level surface with the rim up on two small blocks of wood that are exactly the same height. Measure the distance from the axle to the surface under. The should be the same flip the wheel over. Check this against the stand to be double sure. I do this and I think it is more accurate than dish tool but you can't chech with the wheel on the bike. You can make a dish tool pretty easy too if you want.