2002 Gem E825 here…Stock wheels and live on steep hills. Looking to upgrade wheels and tires. Seems most upgrades are 14" rims that go up to nearly 22" diameter. I know that will change the top speed potential if programer is upgraded, but i am concerned with hill climbing. Anyone stick to upgrading but stock wheel diameter size? Little nervous about dishing up money on larger wheels just to have worse performance will hill climbs.
Also, a motor upgrade is in future too.
Your concern is well founded and correct. Stick with the 21".
You also mention a bigger motor. This is not the solution. But it may be a part of it. What you need are shorter gears. The 02 should have a 10.35:1. It sounds like you would benefit from a 12’.44:1.
As for the motor, the stock “short” GE that was used from 00 to 04 and sometimes found in 05s (I would guess the were just using up inventory) is rather anemic .
A better motor will help you, but it won’t solve the problem . The gears are your starting point
There is much that goes into building a car to suit a special purpose beyond the original 18 holes and home.
The first Q you should ask yourself is - How is it working in it’s present config?
and we can go from there.
How are your batteries working? What are you running and how old are they? Having a good set is probably the best upgrade anyone can do. You’d be surprised at how far Voltage drops when pulling 200~300a out a set of wet cells(climbing hills).
A gearbox swap is a good idea. It’ll pull hills better but your top speed will be affected.
A bigger set of tires(when paired with a gear set) will make the ride a bit nicer (more sidewall flex)
A motor upgrade is not a bad thing to have in future plans.
-Batteries are brand new. Needed to do that first.
-How much does a gear swap change the top end? Are we talking 2-3 MPH or much more? I know it depends on lots of factors, but just a ballpark.
-Good to know as i will be getting new tires soon, so looking at various sizes and wondered about sidewall sizes. Not looking for a hard riding low profile look.
-Yes, motor upgrade in future too.
How much top end do swapping gears impact?
Yeah, with the stock short GE at 4100 RPM, and 21" tall stock tire height, going from a 10.35 to a 12.44 will cost you about 3MPH at the top end, but depending on the controller programming, you might not see a reduction, if it allows the motor to be be spun a bit faster, you’ll still get the stock 25mph max.
But then also climb a heck of a lot better with or without upgraded motor?
Yes, that is correct.
How would 215/50-12 work, fit and ride on a gem?