Ieat4strokes Posted March 25, 2009 Report Share Posted March 25, 2009 I have 21x7x10 fronts and was wondering what do I input for the tire size into the Vapor? Im guessing it wants mm? not sure....... Thanks Quote Link to comment Share on other sites More sharing options...
evro Posted March 25, 2009 Report Share Posted March 25, 2009 hey dude, read your other post. shitty deal man. hope it all works out for you and your family. hopefully i can help a brother out here. i was surprised that a product made in the states asked for metric inputs. you can still program it to display and record in mph but the mm (millimeter) shit surprised me. luckily, us kooky canucks use metric measure. there are 25.4 mm in 1 inch. I calibrated my vapor to a 19 inch front tire but i just installed 21's last week so i\m gonna have to recalibrate to 21 as well. Instead of relying on the tire height to be an exact 21 inches, i measured from the ground to the top of the tread. It will be close to 21, but likely give or take a little. one thing to consider as well is that at speed, tires will get narrower and taller so a slightly higher than actual sitting measurement may end up being a little more accurate. preferred psi has a slight affect also, but not drastic enough to compensate for. if you have access to gps, then just start with the 21 inch measure which will give you an input of approximately 1675. then go out and compare the vapor to the gps. if they're close enough for you, you're set. if not, then measure the front wheel height exactly and insert it in the formula below. plug the new input into the vapor and compare it against the gps again. you can use the range between the two input #'s to fine tune. tire height in inches X 25.4 X 3.14 = vapor input for example 20 3/4 inch tire height : 20.75 X 25.4 X 3.14 = 1655 21 1/4 inch tire height : 21.25 X 25.4 X 3.14 = 1695 that kind of gives you an idea of the range you may have to play with. that 1/2 inch difference in tire height gives you about 40 mm difference in tire circumference that you can use to fine tune. just got another 6 inches of snow here so it will be a few more weeks before i can get out and recalibrate mine but hopefully this gets you on the road. good luck bro Quote Link to comment Share on other sites More sharing options...
Ieat4strokes Posted March 26, 2009 Author Report Share Posted March 26, 2009 dude this thread got pushed way down and i just now found it...... i appreciate the concern and thank u for that! Fuckin Bush, basically threw dirt on our asses when we were already in a hole..... but thats another subject. At least Obama is trying to help out us middle class blue collard workers.... appreciate the detailed responce as well, makes perfect sence now and actually is maybe a mph off or so..... thatll work for me.... my garmin reads about 3mph slower than all my vehicles so i dont know whats right. thanks again man! Quote Link to comment Share on other sites More sharing options...
BansheeDan Posted March 26, 2009 Report Share Posted March 26, 2009 my garmin reads about 3mph slower than all my vehicles so i dont know whats right. Thats strange....my TomTom reads the exact same as my speedo in my truck. Dan Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted March 26, 2009 Report Share Posted March 26, 2009 I did mine the manual way. #1 Make sure you have the proper amount of air PSI in your tires. Make a mark on the road where the valve stem is down. With you stitting on the banshee roll it letting the tire make 10 revolutions, ending with the valve stem at the bottom again. Meausre the distance between marks. Divide that meaurement by 10 this gives you the average diameter of the tire. The more revolutions you do with the tire the more accurate your measuement is going to be. Just divide you total lenght by how many revolutions = average tire diameter. Then take your tire diameter x 25.4 and it will give you your tire diameter in mm's. Quote Link to comment Share on other sites More sharing options...
vulvafan537240 Posted March 26, 2009 Report Share Posted March 26, 2009 i measured my tires and put the measurement in and it was way off. i used a handheld gps and got it pretty close. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted March 26, 2009 Report Share Posted March 26, 2009 how did you measure them? Quote Link to comment Share on other sites More sharing options...
vulvafan537240 Posted March 27, 2009 Report Share Posted March 27, 2009 how did you measure them? with a tape measure from the ground to the top of the tire Quote Link to comment Share on other sites More sharing options...
TwistedSheeRida Posted March 27, 2009 Report Share Posted March 27, 2009 haha measureing from the ground to the top of the tire is the most in accurate way you could do it. roll the tire like jbooker82 said thats the most accurate your gonna get Quote Link to comment Share on other sites More sharing options...
vulvafan537240 Posted March 27, 2009 Report Share Posted March 27, 2009 haha measureing from the ground to the top of the tire is the most in accurate way you could do it. roll the tire like jbooker82 said thats the most accurate your gonna get its all good now. the gps is pretty accurate. Quote Link to comment Share on other sites More sharing options...
evro Posted March 27, 2009 Report Share Posted March 27, 2009 its all good now. the gps is pretty accurate. X2....gps correction is the most accurate method (including radar). it may take a little longer, but another 15 minutes was no big deal to me. Quote Link to comment Share on other sites More sharing options...
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