Bad Speedo

I can't seem to figure out why my speedo is so far off. It is off by a good 4 mph. I held a gps to it at 50 and it said I was almost going 55. I have the right size tires on all 4 wheels, which are stock right now. Would a new gauge cluster help? Are there any adjustments I can do? My tires are old but i don't think they could be causing a wrong reading of 4 mph. Any help would be greatly appreciated.

By govt. regulation a speedo can be off by 10%, so at 50 mph you could be off by about 5 mph and still be good...


gunnmen01

Well i'm gonna get new wheels and I want to have closer tolerances than "4mph off to start with" , and i know that most cars come 2mph fast to make people drive slower. But this is really noticeable. I would like to put in a different gauge cluster but i don't know if it will help. If it would help i wouldn't worry so much about the tire size on my new wheels and fix the gauges later.

do you still have the factory wheels and tires on thecar ?

Yeah they are still stock for the moment, i'll be changing them when it gets warmer because i don't want to wreck the wheels with salt. I have a month or two to figure this out.