Astro Van

Incorrect tire size (larger diameter tires) is one possible culprit. My question though, is at what speed is your speedo supposedly 5km off? It won't be off by 5km/h across the entire speed spectrum. Any error will be a percentage error, so the amount that it is off will increase as speed increases. I'd require more information from the inspector.

There was a speed sign on a road and on the dash I was doing 64 and the sign said 59 this was done when the van was driven for 20 min and then I tried when the van was just started up and it read close to what was on the dash. Could the clutch fan cause this problem it sounds a little rough The original tires that the van came with are 215 75 15 and I changed them to

There was a speed sign on a road and on the dash I was doing 64 and the sign said 59 this was done when the van was driven for 20 min and then I tried when the van was just started up and it read close to what was on the dash. Could the clutch fan cause this problem it sounds a little rough The original tires that the van came with are 215 75 15 and I changed them to