Trailtech Speedo ??

[Evan]

I have a trail tech speedo and I recently changed tire sizes and it has affected my speedo as expected. The first time it was setup perfect with 21 inch tires I now have 20 inch tires and I meassured the same way I did with the 21s and it is still way off. Does anyone know the measurement they put in for 20 inch tires. I have tried several different ways of measuring the tire and followed thier instructions to convert it but it is still wrong, saying my top speed is 105. :huh Any help would be appreciated.

[FatBoy Redrider]

I'm pretty sure they have a website. You could try to get some info there...

[JOEX]

Dang! Them are some fast tires.:D

It might not make that much of a differance but do an actual measurement of the tire. Don't go by what it says on the sidewall, some tires aren't exactly what they say they are.


Joe

[Evan]

You mean like take a tape measure and wrap around it:D Seriously I measured them by putting a mark on the tire and a mark on the ground then rolling it one full revoulution and put another mark on the ground and measured from mark to mark to come up with the measurement. This is how I did it with my 21 inch tires and got the right reading. I think I will try and measure again at least 2 more times and see if I dont come up with something different. I am just wondering if anyone has 20 inch tires and a trailtech speedo what are your measurements?

[Atomic83]

Just measure the diameter of the tire and then use the formula it gives you to find the circumference, and convert it to millimeters (or what ever you have to convert to). Your conversion or measurement is way off if your getting 105mph.

[400exBro]

are you sure you didn't convert mph to km/ph, happen to a friend of mine till he figured it out.
You never now

[Evan]

OK I measured the outside diameter with one of those flimsy tape measures like the tailors use, anyway, at the center of the tread all the way around the tire is 60 inches 60x25.4 is 1524 right I punched this in and it is way off. So I think I will do it the other way tommorrow.

[Evan]

OK listen up all you smart people.

Method A)
Mark a spot on the ground with a spot on the tire and roll the wheel on full revolution. Mark another spot. Measure from each spot on ground and convert to mm by multyplying inches times 25.4 This is your wheel size.

Method B)
Measure from top of tire to ground. Mutiply that times 25.4 to get mm. Mutiply that times 3.14 to get your wheel size.

I have tried both ways. Method A I get 59.5 inches. which is roughly 1511 mm, which is the size I should punch in and the speed is defintely wrong. Method B I 18.75 inches times 25.4 times 3.14 = roughly 1495. I have tried punching in both of these numbers and it still give the wrong reading for speed. Yes I have checked the MPH thing and it does defintely say MPH not KPH. Today I just estimated the number to be put in to even be remotely correct it would have to be in the 1000 to 1100 range. I am beginning to wonder if I didnt recieve a faulty computer. Tomorrow I am going to try using KPH instead of MPH and see what happens. When I had it on 1125 I think it was saying top speed of 55 but then I went and cleaned my air filter and took my airbox lid of and it jumped to 81 :huh strange. Any suggestions??

[Atomic83]

Mine is set up at like 1100 someting or 1200 something (can't remember) with stock tires so your total should be lower than mine if you have smaller tires. I don't have my intructions here with me or I would help you. Read those formuals again and make sure you are doing everything right. Method B is the easiest way to do it.

[JOEX]

Do you still have the 21" tires or remember the measurement numbers from them? If so, maybe you could subtract the 1" conversion from those numbers and use that to get close. Or you could hook it up to somone elses quad to see if it is a computer defect. Just some ideas. I'm hoping to get a trail tech sometime so i'm curious as to how this turns out.

Joe

edit- Damn, I type slow.

[Evan]

I had 21 inch holeshots and the # was 1411 I tried the subtract 1 inch thing but it didnt work. Atomic which method did you use? I am thinking of doing the set distance method where you take a car that you can rely on and drive 1 mile then drive 1 mile on the quad and you do some fancy math and walah you have the correct measurement.

[Atomic83]

I used method b and it seemed easy to do. Yeah, you can try the car thing that might be your only option, but like I said, check and make sure your doing you conversions right (inch to millimeter & diameter to circumference). But whatever you do, Good Luck.