Speedo in my 87 pickup 4x4
 

I got some bigger tires and wheels for my truck and as a result my speedo says I'm doing about 20 more than I'm actually doing. How can I fix this. I don't want another speeding ticket.

Re-gear your axles is the best all around option in my opinion, but gets spendy if you have to pay someone to do it. Try finding a speedometer/gauge shop in your area and see if they can do something for you.

Ok thanks I'll try that.

buy a small cheap GPS and velcro it in.