TC6.2 is fine out of the box. I would go to petitrc.com and find some other asphalt set ups for that car on there. That will help with a starting point on: tires, shock springs, shock oil weight. After that just run and make your adjustments from there. For asphault i suggest starting with LTCR body as well.
Also came from off road and 17.5 off road is not like 17.5 on road. The weight issue is not that big of a deal as the 17.5 is plenty fast in on road.
TRF 418 - Team Powers 17.5, HobbyWing Stock Spec, Xpert servo
Xray T4 2016 - Trinity D4, HobbyWing Stock Spec, Ko Propo servo and radio
KustomRCGraphics.com (Best looking novice on the track)