ditto what timmah said.
For the most part, as long as my temp is 200+ but not more then 270 and I am getting good power and smoke from the exhaust, I consider it properly tuned.
ORIGINAL: Timmahh
your running temps will vary from day to day and even hr to hr depending on alot of things like outside temps, humidity, percentage of nitro used, tune ect... but typically standard operating temps are between 210 and 260, with about 250 being optimal. BUT dont tune by temps tune by performance and sound. as long as your pretty steady UNDER 270 things should be good, above 270 and your getting warm, over 300, its time to shut it down for a few. Use a temp gun for guidence, not religion. and dont use onboards, theyre not reliable and often cause some other issues.
hth
Timmahh