Parametre for Low RPM Limit

Hi, i not arrive to parametre my VESC to have Very Low speed limit or low RPM limit.
I try to made en small car for my son.
The car is made with Hoverboard hub wheel 8 inches 350W with capteur Hall and have Battery 7S3P 24v 9,6Ah/ 3C descharge.
My target is to have 8Km/h max so around 210 RPM  limit with wheel of 8 inches. And i would have very smooth start and progressive acceleration with thumble throttle.
Can you help me to parametre in VESC tools ? 
First in Motor Setting :
In the Parametre "RPM" in MAX ERPM, i'm not arrive to find the good valu and in  "ERPM limit Start " what % must can i put.
When the valu is to low the wheels not have smooth rotation.
In "FOC"  there are "sensorless", "hall sensors", "encoder" i must change somthing there too ? i see in different place ERPM so i must change things here ?

Second in App Setting in "ADC"

I use tumble throttle 5V from Escooter and i add resistence to have 3,3V out put max.
Maybe we will see that is second time if this is ok or not.

Thank you for this site and all the work you do .
This VESC project are really cool and give lot of new possibility
I read lot of thing in the forum about programming the VESC to have best preformence but not find a post for the probleme i have.

Ilan