trailer aid ramps

[snowbirds R us]

Has anyone used the "trailer aid" ramps to drive onto to raise the axles and change out a flat tire on a large rv like the Montanas? Some of the reviews that I have read, state that it does not raise the affected axle high enough and others say it is great. I guess the great responses might be from those users with a smaller trailer. I was going to make me some ramps out of 2x8's but though the store bought ones would be lighter. Any thoughts?