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How do I read the NGK spark plug codes?

PFR7B-11 is a typical colder plug for the TT. Coding from left to right:

Plug Type

I	Iridium Platinum
L	Thread Reach 26.5mm
P	Premium Platinum
Z	Extended Gap

Metal Shell Size

F	ø 14, 19mm (3/4") Reach, 16mm (5/8") Hex.
G	ø 14, 19mm (3/4") Reach, 20.6mm (13/16") Hex.
J	ø 12, 19mm (3/4") Reach, 19mm Hex.
M	ø 10, 19mm (3/4") Reach, 16mm (5/8") Hex.
T	Tapered Seat ø 14, 17.5mm Reach, 16mm (5/8") Hex.
PTR5A-13	ø 14, 25mm Reach, 16mm (5/8") Hex.

Construction

R

Resistor

Heat Range

2	Hot
down to
11	Cold

Firing End Construction

A, B, C... Special Design

Gap Width

8	0.8mm (.032")
9	0.9mm (.036")
10	1.0mm (.040")
11	1.1mm (.044")
13	1.3mm (.052")
14	1.4mm (.055")
15	1.5mm (.060")
20	2.0mm (.089")