Yes, you can over do the weights. Not knowing what model you have, but I'm guessing that 50 pounds of wheel weights on each side would be about max. Remember that the tranny has to spin the wheels and the added weight does put a strain on the tranny in getting it up to speed AND slowing it down. Liquid in the wheels is good as it is not locked to the tires, it's free to slosh around eliminating most of the stress on the tranny.