moreno510 Posted December 28, 2003 Report Share Posted December 28, 2003 playin about with my flashy new gps system tonight i noticed that the speed reading on it was 9 mph less than my speedo in my car at only 60 mphis this round about the usual ? Quote Link to comment Share on other sites More sharing options...
twisty b-road Posted December 28, 2003 Report Share Posted December 28, 2003 Yeah that's about what my speedo/road angel says as well.70mph on speedo = 61/62mph on road angel79mph on speedo = 70 mph on ra79mph on road angel (10% + 2mph) = 89/90mph on speedo*ahem* 125mph on speedo = 110mph on road angel Quote Link to comment Share on other sites More sharing options...
bossjohnc Posted December 28, 2003 Report Share Posted December 28, 2003 What kinda wheels u got? AIUI smaller (?) wheels would have that effect... Quote Link to comment Share on other sites More sharing options...
twisty b-road Posted December 28, 2003 Report Share Posted December 28, 2003 Both my sets of wheels are factory size (6.5x15, 205/45/15) Quote Link to comment Share on other sites More sharing options...
bossjohnc Posted December 28, 2003 Report Share Posted December 28, 2003 That's a hooj speed difference... u sure your wheels aren't still spinning? style="vertical-align:middle" emoid=";)" border="0" alt="wink.gif" /> Quote Link to comment Share on other sites More sharing options...
Alan VW Posted December 29, 2003 Report Share Posted December 29, 2003 its normaly about 3 miles out with the cos the way it calabrated, but i wouldnt chance sayin that to a cop :sarc: wheels is the biggest thing to have an affect on it, if your car come with 17ins and u put 15ins on... for example the wheel roates quicker cos of the circumfrance of the wheel Quote Link to comment Share on other sites More sharing options...
`99-Acura`-Integra Posted December 29, 2003 Report Share Posted December 29, 2003 bigger or smaller wheels then factory tires, will effect your speedo reading, there is a device that plugs into your computer in the car that can fix that problem, not sure then name of it or the price but its out there. It can also increase your HP by anywhere from `1-25` Horses, depending on the size of your engine. Quote Link to comment Share on other sites More sharing options...
Dave_M Posted December 31, 2003 Report Share Posted December 31, 2003 Had the same kinda reading of `8-9mph` less in a turbo'd scooby Impreza, no wheel mods, nothing. I hear this is usual in cars, as it will keep your speed down (yeah right!) I dunno if this would be allowed though? Quote Link to comment Share on other sites More sharing options...
RobinA3 Posted January 1, 2004 Report Share Posted January 1, 2004 there should be `1-5` mph difference really depending on the speed you are going, higher the speed bigger the difference, seems strange Quote Link to comment Share on other sites More sharing options...
alexfernihough Posted January 1, 2004 Report Share Posted January 1, 2004 thats why speed cameras allow for something like 4% and 4mph over the actual limit or something like that.i think top gear did a test on some cars using fancy timing equipment and stuff and found out that no speed ois anywhere near acurate.when u were using u'r gps did it have 6 satalites if not then it is not 100% accurate but with 6 satalites it knows almost to the cm where you are. Quote Link to comment Share on other sites More sharing options...
Crusoe Posted January 5, 2004 Report Share Posted January 5, 2004 FYI Unless it is a time of war (when the encryption was removed last time) there is a deliberate scrambling of the GPS signals to make `non-military` GPS systems accurate to + or - 4m.I believe the European law for the manufacturers is + 4% to – 10% on the accuracy of car speedometers though someone can look up the law on the web if they are interested. They are obviously going to err on the side of under reading, think when they tested a few Porsche was the best with a 3% under reading but most are `7-8`% under. By law the police give you at least 5% over the limit to allow for the speedo. Even the standard Gatso is out by `2-3mph` from the inside to the outside lane if it is a dual carriageway, your less likely to be done in the outside lane.Welcome back to work everyone, happy new year and all that :thumbs: Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.