http://www.atsdr.cdc.gov/toxprofiles/tp85-c4.pdf

coal-tar creosote ignites at 335º C (635º F).

for comparison, wood and paper ignite at about 233º C (“Fahrenheit 451”),

and lead melts at 327º C

Another reference:

http://cameochemicals.noaa.gov/chris/CCT.pdf

gives ignition point at 637º F

4. FIRE HAZARDS

4.1 Flash Point: >160°F C.C.

4.2 Flammable Limits in Air: Not pertinent

4.3 Fire Extinguishing Agents: Dry chemical, carbon dioxide or foam

4.4 Fire Extinguishing Agents Not to Be Used: Water may be ineffective.

4.5 Special Hazards of Combustion Products: Currently not available

4.6 Behavior in Fire: Heavy, irritating black smoke is formed.

4.7 Auto Ignition Temperature: 637°F