Technical Faulty Speedo Help!

[houlty]

hi guys im new hear, but having mad problems with my 01 sei, speedo is out by bout 10 mph

(so when the speedo reads im doin 20 im actually doin 30)

any 1 had this issue and know where i can try, cause arnold clark are in my books after they ****ed my mot up!

 

[AppleSei]

Could be a faulty speedo, however do you have bigger aftermaket wheels on, as the speedo can be inaccurate if the wheels are non standard.

Will let J333 EVO (aaron) have the floor