Figuring out Truck plates is a work in progress. Information provided here is a working theory.
Believed "private" truck information in left column; believed commercial in right column.
First issue 1921, when Weight Codes introduced.
All plates expired October 31 of year marked. 1/2 year same as passenger 1934-1936; Earliest truck-specific 1/2 year known 1956.
Believed "private" truck information in left column; believed commercial in right column.
First issue 1921, when Weight Codes introduced.
All plates expired October 31 of year marked. 1/2 year same as passenger 1934-1936; Earliest truck-specific 1/2 year known 1956.
Plates marked with TON but no leading letter believed to be Trailer (prior to 1965)
Restamped plates known 1943, 1948, 1951
jump to modern era: 1982-present
weight-based letter coding used 1921-1971
| LETTER | TONS (up to) |
years verified |
| H | < 1 |
1921-1971 |
| I | 1 1/2 |
1921-1938 |
| J |
TON |
1930-1960 |
| K |
2 1/2 |
1924, 1927 |
| L |
3 |
1934-1958 |
| M |
3 1/2 |
|
| N |
4 |
1927-1956 |
| O |
4 1/2 |
1926 |
| P |
5 |
1954+, used with specific weight |
| Q |
>5 |
1926 |
1921 (single) red/black  black/white  white/dark green  script "SC" in circle black/orange  white/green 1926 (single) "SC" inside Palmetto Tree design green/white 1927 (single) "SC" inside Palmetto Tree design green/white 1928 (single) black/yellow 1929 (single) black/white  "IODINE" vertically on right side white/black  "THE IODINE STATE" bottom green/gray  "THE IODINE STATE" bottom black/yellow 1933 (pair) "THE IODINE PRODUCTS STATE" bottom black/white 1934 (pair) "APRIL 30" top or "OCTOBER 31" bottom black/yellow(April) yellow/black(October)  "APRIL 30" top or "OCTOBER 31" bottom color variations: red/white; white/red; black/white; white/black no rhyme or reason known as to color variations  "APRIL 30" top or "OCTOBER 31" bottom yellow/black(April) black/yellow(October)  unknown if APRIL exists - all I've seen are OCT black/white  black/yellow 1939 (pair) black/white  yellow/black 1941 (pair) black/yellow 1942 (pair) yellow/black  restamped from collected plates - most '42; rare unstamped exist no letter, assumed overflow of H-class yellow/black  strip applied to existing 1943; weight class matched, plate number did not yellow/green 1945 (single) yellow/green  silver/black  black/yellow some restamped known (shown)  yellow/black  white/black  black/white first year actual weight marked on plate
  white/black some restamped know (both shown)
 yellow/black  black/yellow begin P-prefix for variable weight (Commercial vehicles)
other letters for Private vehicles
 white/black  black/white  black/yellow  white/blue 1958 (pair) blue/white  white/blue 
 blue/white  red/white last year weight marked on plate (H only)
 white/red  white/green  begin 2-letter prefix, (overflow from single letter) white/black  black/white  white/blue P-prefix dropped, but still considered Commercial
  blue/white transition to smaller font begin P-prefix for private/weight-based tax
weight-marked considered Commercial
  begin reflective letters white/black  white/blue   "1670 300 YEARS 1970" white/green   white/brown  white/black  white/blue weight codes discontinued; previous "H" truck get regular random-issue  last year for pairs white/green  white/maroon Era 1976-1981 all single plates  "1776 Bicentennial 1976" top blue/white  red/white  green/white  black/white 1980 blue/white  red/white | 
  I believe wrong colors           non H, opposite colors?            
               
                        1/2 year changes to May 15 First year??  
essentially same as above, but high weight codes receive leading letter        1/2 year changes to June 30 First year??   > forward to 1982-present |
