Quote:
Originally Posted by usgicollector
205/65-10 tires work very well on a non lifted RXV cart.
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That would be a good choice. That works out to a mathematical tire diameter of about 20.369". He may want to keep his 14" wheels.
Jroc118... if you would like to keep your existing 14" wheels, using a tire size of 205/40-14 would give you a mathematical tire diameter of about 20.381".
The maximum sized tire to keep within the operating range of the E-Z-GO VCL (Vehical Control Language) in the RXV controller is 20.5". That is also the maximum tire size for use without a lift.
The following is for the benefit of anyone unfamiliar with the workings of EV 3 phase AC drives. Unlike DC motors, with 3 phase AC motors, the controller controls the drive frequency to control motor RPM.
The purpose of the VCL range is so that the controller can properly calculate the drive current required to maintain rotor lock in the motor at the operating RPM. With AC drives, in order to be most efficient and minimize overheat of the controller and motor, you'll want the controller to be able to calculate the minimum amount of current required to maintain synchronous rotor lock with the rotating 3 phase magnetic field throughout the operating RPM range of the motor. Not enough current results in excess slip, and your motor turns slower than the field rotation speed. Too much current wastes energy and results in excess heat generated in both the motor and the controller.
When the tire diameter is much larger than the VCL range, it requires a lot more current to maintain lock than the VCL can calculate that the motor should require at any particular RPM. This results in conflicts that cannot resolve, which affects operation. Even if you were to have your controller recalibrated for the larger tire, the higher current at lower RPM will overload the controller and motor, resulting in higher temperature operation than the controller and motor were designed for.
What we have seen with stock RXV controllers and 23" tires, they tend to overheat and shut down more often than not, before the motor reaches overheat. After multiple overheats, the controller will fail. A higher powered controller can prevent controller damage/failure, but will do nothing to prevent motor overheat. The controller will detect the motor overheat, and cut back on drive, resulting in cart slowdown.
There are members here running 23" tires on their RXV with no apparent issues, and that may have a lot to do with how and where they operate them. I know of a couple that use 350 Amp upgrade controllers. But I've also seen quite a few RXV owners that have had issues caused by 23" tires. This is why I try to warn others about it.