Depends on what year Gem you have. 2000-2004 have horrible suspension. Big wheels make it much worse, rides really hard. 2005 was a big improvement. up to 16", 50 series tires, ride well. 2013+ another big suspension upgrade. 17" with 40-45 series work. Gem above 205-50-16 . One I did last week 195-45-17
Thanks.
I have a 2014 with 14". Occasionally the ride feels a bit jarring. I have owned sports cars, so low profile is more in line with the look like. I don’t see a huge advantage on a GEM going to a 205 from a 195 (less rotational mass is better). I was wondering if there are any issues with rubbing using 205s and stock suspension? Also looking to go with an AC motor down the road and want to make sure that clears.
Thanks again.
Yeah, we used the rings when we had the right ones in stock 
They did help fix vibration issues when we had installed without them.
all-in-all, when you factor GEMs being light, relatively small wheel/tire packages, low speed and generally fewer miles driven I can see why there aren’t more issues. But I’ll be looking for the right spacer/wheel/tire combo when it comes time.
The 205’s filled back fender perfectly(one of the goals) the other was as tall a tire I could fit. I kept the factory dc motor and wanted to get 45mph out of the setup. The front rubbed some on inner fender well, tweaking with small spacers might have fixed it. I choose to cut the plastic inner fender some (easy job). The wheels I wanted where 7" and the 205’s gave it the square shoulder look, just did one of my other Gems with 195/45/17 , 7" wheel and the tread tappers in some, don’t prefer the look. I can post pictures of both but since you were in the business you can probably see this all in your head.
I am still learning about the different motor/battery setups. Right now I have OEM motor (7.5HP?) and batteries with magic magnet. 185/60R14 tires.
I get 33MPH which is pretty close to all I need. 35 would be ideal eventually. Your original DC motor can handle the RPMs at 45MPH?
I have a tall bridge that I have to go over and I struggle to get up then it does not seem to like going downhill at 35+ so I let off the “gas” and coast at about 30MPH.
I am not sure if there is some maintenance/mod I can perform on the DC motor to handle higher RPMs?
2014 gear ratio with those tall tires I put on will let it hit that speed(maybe more) I doubt it would survive long If used at that speed often. I rarely drive over 40, mostly in the 35 mph range. The black 7.5hp is one of my favorites, did a big motor shoot out( it is on here) and it tied for first place. My lithium pack fully charged is 97v and it handles it well. A few things you can do to increase your top speed. Inflate tires to 35 psi, highly recommended. Have your controller reprogrammed for higher speed. Install a lithium pack. The black motors have a common problem. The clearance for the brushes is a little to small. The brushes will eventually get stuck in the housing and not make good contact. High probability you already have some like that. You can pull the brushes and service the motor if you are a DIY guy or send it to @Old_Houseboater , he has done hundreds.