A lot of variables for 1 straight shot diagnosis.
Get a temp guage if you are parranoyed with overheating like I am.
Temp gun or Venom on board temp guage.
200-220 optimal. max 270.
I remember with my pullstart, sometimes I'd draw too much fuel in and that floods the engine & overhwhelms the starting power of the glowplug. If that happens you'll notice the piston is tighter in there when pulling the start. If so take of the glow plug, put a paper towel over the head and pull the start again. That should shoot out the flooded fuel. Otherwise, no towel over head= nitro shower.
Check your glowplug and make sure its shiny. Not burnt.
Also use a rechargeable battery on your glow plug igniter.
Make sure you have a good connection with the plug.
The 2 speed. Read the 2 speed instructions and re set the set srew via the directions until you've followed them perfect. Use Thread lock on the set screw so that it doesn't keep losing it's shift point. After tightening all the way down (With my RS4 2) unscrew 3-3.5 turns (3.5 if high performance engine), so yes 3.5 turns for 18SS (if that's what you got).
The tire wear could be from anything. If its on the same side as your shock and 2 speed, you might of hit a rock or something if I can imagine right...I've had a tire rip apart after I NICKED it with a hobby knife and ballooned it on the starter box. Keep a new tire set on hand....it will eventually go, but don't worry I'M ROOTING FOR IT TOO!!
P.S. get after run oil to drop into the engine at the end of the day to absorb the old fuel inside if you care for the engine. & keep your air filter oiled.
Just break down and buy both...
Byron's & Odonnel fuel is much better than the blue thunder too.