I wouldnt buy new trucks. You could use more speed rings (is that what the axle washers are called? Why?) to push the wheels out further if you wanted. Ive seen people go up to 8.75 trucks on 8.38, but 8.5 trucks seem to be the most popular. I bought an 8.38 semi recently and the shop recommended 148s, I bought 149s, wish I bought 148s.