Okay. So, you can get in a grow at that level. No, its far from optimal. 20-25c is a much more desirable level.
If you have a tent. I guess you're using an exhaust.
So, I suggest you put your exhaust on a timer, only to vent every 5mins out of every 30m r so. This will keep your temp up. If you're not using an exhaust. You can turn your light up to 100% for heat and keep fans away from lights/driver and you'll not any have issues with temp.. for lights off. I suggest they go off at the warmer part of their day in your garage. Tweaking things like this is really easy. And will solve any small issue with big consequences if not done.