Why do speedometers read high?
Traditional speedometers don’t really measure a car’s speed. They’re just an rpm gauge for the drive wheels, because that’s where they get their information—typically from a drive cable or sensor on the driveline. Add a few passengers and their weight squishes the sidewall further, causing the speedo to read high.
How accurate is the speedometer in a car?
The odometer shows the distance your vehicle has travelled, while the speedometer show how fast your vehicle is going. “The accuracy of the speedometer in most vehicles, including Volkswagens, is generally within a few percentage points of actual speed,” Tetzlaff says.
What should the speedometer read at 70 mph?
When traveling at a true 70 mph, as indicated by our highly precise Datron optical fifth-wheel equipment, the average speedometer (based on more than 200 road-tested vehicles) reads 71.37 mph. Wait, wait! Before you roll your eyes and turn the page, let us dig just a bit deeper and reveal some dirt.
Why do I need to advance my speedometer?
EU regulations require speedometer advance. Speedometer advance is necessary to compensate for the negative tolerances in tire sizes between tire manufacturers, electric speedometer indication, and other factors. This advance reduces the risk of the speedometer displaying a speed that is less than the vehicle’s actual speed.
Why does the speedometer read higher with bigger tires?
When you go to bigger tires the circumference of the tires is larger, meaning the distance around the tire is longer. Thus, with each revolution you are traveling further than before. Therefore your actual speed is higher than your speedometer reads.
Why does the speedometer read how many revolutions?
Your speedometer is reading how many revolutions your tires are making not how fast they are spinning. When you go to bigger tires the circumference of the tires is larger, meaning the distance around the tire is longer. Thus, with each revolution you are traveling further than before.
When traveling at a true 70 mph, as indicated by our highly precise Datron optical fifth-wheel equipment, the average speedometer (based on more than 200 road-tested vehicles) reads 71.37 mph. Wait, wait! Before you roll your eyes and turn the page, let us dig just a bit deeper and reveal some dirt.
What do I need to slow down my speedometer?
“If you need to slow down the speedometer, you need more teeth on the driven gear.” For example, if your speedometer is showing 60 mph and it should be showing 52 mph, you will need to use a driven gear with more teeth to spin the speedometer cable slower. In this case, you need to add three teeth.
When you go to bigger tires the circumference of the tires is larger, meaning the distance around the tire is longer. Thus, with each revolution you are traveling further than before. Therefore your actual speed is higher than your speedometer reads.
Your speedometer is reading how many revolutions your tires are making not how fast they are spinning. When you go to bigger tires the circumference of the tires is larger, meaning the distance around the tire is longer. Thus, with each revolution you are traveling further than before.