[JohnnieB]

Those do look like automotive cables. Also, the batteries don't appear to have any hold downs.

With 23" tires, you lose 22% of the available torque where rubber meets road, so the cart will slow more on hills than it would have with stock (18") tires. Also, if the off-road tires are the low pressure type (<10PSI max inflation pressure), even more slowing will occur. Not counting the inflation pressure issue, if it exists, you'll need 28% greater than stock torque at the motor to climb the same hill at the same speed as the same cart with 18" tires.

The good news is that going to 48V will increase the torque at the motor by 33%, so a higher torque motor might not be needed if the uphill speeds are acceptable to you.

A new set (10 of them, you id them correctly) of cables, a higher amp throughput controller and solenoid will also help, however most of the increased torque from installing a higher amp controller is at the low end of the RPM spectrum. How many amps a motor draws is dictated by by the motor's RPM and the bulk of the gain from a higher amp controller occurs below the max RPM at which the motor is capable of drawing more amps than the stock (275A or 300A) controller can pass, but with the taller tires the motor turns slower for any given speed, so the net result isn't quite as bad.

The path forward is still the same, with one more step at the end. If cart doesn't do what you want it to do with stock motor at 48V, a new motor will be needed. Lots of choices out there, but I don't know what is available in Canada. Same with cables and other parts.