Finished and have one more question...

[oconnorb]

I need a reflection on how the “speed” numbers are supposed to add up. 48V CC with upgraded or modified 36V motor, not sure what the rewind shop guys did to it for I am not an electrical rebuild kind of guy, just provided the pizza and beer and then installed when they gave it back. Updated to all the HD stuff and new controller, but the speed difference in changing tire sizes and a few adjustments are bothering me. Got the last tire and rim back late yesterday, got permission to run the EW runway this afternoon to do a “speed” run on my LSV (97 CC DS), bleed the disk brakes for the pads were dragging on the rotors, re-aligned the front (toe in) and adjusted the rear end to run “square” with the front, for it had a little “dog leg tracking” to it, then loaded up on the trailer and off we all went. Prior to changing the tires, we were running 38.6 to 38.2 mph on a full charge and it would drop as we completed more passes, at times faster with a good tail wind. Changed from 20550R/10 to 25550R/10 and we are now running 44.8 to 44.4 mph on a full charge, again dropping as the batteries drain.

Question is this normal for tire change, I didn’t expect to have such an increase in the speed. There was no wind this afternoon, so I can’t press this to “tail wind” addition… For those who are more into the # crunching, can you point me in the correct direction for some chart or formula to review overall process? Not wanting more speed, but this project is official completed, I know they are never supposed to be done, but I have all items installed, removed or tweaked to there is nothing else I can change unless I add a bicycle handlebar bell vice the horn.

Thanks, funding support will be forth coming for site administrator, everyone with their input, good and bad was very helpful in the overall break down and rebuild of this project… For those starting out, from the original $300.00 it cost for the cart (running), to the over $6,300.00 I have invested, it has been a blast, granted I have more funding than common sense and several items on this LSV are “toys” but I can justify everyone of them to the spouse as “needed” for LSV certification. Its dark and its late, time to call it a day, I will generate “photo album” in the profile later in the month. Again thanks for everyone’s support and answers to questions.

[sonicj]

OK,
Lets first look at the tire diameter...
the aspect ratio = 205mm wide and 55% as tall as it is wide
so..
205 x .55 = 112.75mm sidewall height of the original tire
255 x .55 = 140.25mm sidewall height of the new tire
Now we add the diameter of the rim plus the sidewall at the top and bottom of the tire. 25.4mm in a Inch x 10" = 254mm
254 + 112.75 + 112.75 = 479.5mm total old wheel height
254 + 140.25 + 140.25 = 534.5mm total new wheel height
Thats a gain of 11.47% in tire diameter.

Now, the speed was 38.6 and changed to 44.8mph. Thats a gain of 16.06% in speed.

The error in the percentage increase could come from a number of sources... The tire measurements are rarely consistent between manufacturers and should be considered an approximation, tire deflection, tread wear, tire pressure, etc. Another source could be that you are now operating in a larger portion of the motor's power band. Torque, current, voltage drop, etc are also involved. Imo, its likely a mix of all of the above. So in a nutshell, there is no easy and precise way to calculate this (without a degree in physics and a lot of spare time) as there are too many approximated variables involved and results appear to be non-linear. My 2¢ fwiw.
-sj

[oconnorb]

-sj,

Thanks for info… makes sense, in talking with “co designer” this morning over Mt. Dew and doughnuts… she seems to think the brake pads were dragging too much on the rotors; after we bleed brakes and adjusted the rear tracking, it removed a considerable amount of friction and this might have allowed for part of the increase. Either way, no issues… LSV is being donated to local Wounded Warrior Program, as this was the original plan when we started this adventure… I have learned lots and had lots of fun in the process.

Will look for another DS to "convert" and go terrorize the base police~