These large plates are mostly used on larger commercial or truck trailers, while personal use (i.e. boat, camper) trailers receive the small TL plates.
SEMI (yellow painted) 1998-2003
FEB 03 S-TL (Semi-Trailer) five-year base follows the same format as 1988-1998 five-year bases but with Waldale dies.
SEMI (Hi-Signs) 2003-2005
The white SEMI trailer plate was introduced and replaced all 1998-2003 bases by February 2003. This permanent plate follows the trend of most provinces and states to only pro-rate fees on the power unit as per the IRP agreement of 2001. The initial batch of SEMI plates was made by Hi-Signs in the SG-SL range.
SEMI (Waldale) 2005-2014
Waldale-made SEMI plates followed around 2005 starting at SM, skipping past SN and SP then to SR followed by SX, SY, SZ and the first few TA series plates, confirmed as high as TA-17-95.
Confirmed as low as TA-18-78, Waldale-made SEMI plates appeared on the full-graphic Friendly base, still with sticker boxes.
PSV trailer plates are very scarce. Letters always begin with P and end with L. The first PSV-TL plate issued in 1997 was PAL 001 and by 2007 we had only reached PAL 222, making this an extremely low-issuance type. PAL 355 current (Nov 2014) Winnipeg high and PAL 552 (Dec. 2009, still current) issued in rural areas.
PCL series accidentally produced in pairs and issued as PSV plates in 2011.
PSV-TL Apportioned 2001-
Apportioned variations were discovered on both CT and PSV trailers in 2009. The plates shown in use in the photos above are the only ones I've ever seen.
CT-TL (Waldale & Hi-Signs) 1997-2008
From 1997-2008 the range for CT-TL (Commercial Trailer) plates was CAL-CZL, with the letter L always in the third position.
Only a small number of CT-TL plates were made with Hi-Signs dies in the CPL, CRL and CSL series. What is interesting about these is that the blue coloured printing on the small "TL" legend along the bottom is actually part of the sheeting and not rolled ink like the other raised characters on the plate.
CT-TL (original outline bison) 2008-15
In April 2008, the CAL-CZL range for commercial trailers was exhausted and a new numbering format appeared, with the letter L moved to the second position starting with the CLA series. These were produced with the "outline" bison until the end of the CLP series was reached and issued in 2015.
CT-TL (Black bison) 2015-
The black bison appeared on CT-TL plates starting at CLR 001 in August 2015.
CT-TL Apportioned 2001-
Apportioned variations were discovered on both CT and PSV trailers in 2009. The plates shown in use above are the only ones I've ever seen.