There are several watches that McQueen made popular. Here are the details:

Among wristwatch enthusiasts, Steve McQueen made three particular models famous: the Heuer Monaco, the Rolex Explorer II, and the Rolex Submariner. The Rolex Explorer II (ref. 1655), which was made in the 1970's and early 80's, is very collectable, rare, and referred to as the Steve McQueen Rolex. It is also called the Steve McQueen Explorer or a Freccione era Explorer, or the Steve McQueen Freccione

Dave McDermott gives the following details:   "While it is technically correct that the 1655 Explorer II is often called the "Steve McQueen", it should be noted that there is no evidence to suggest that Steve McQueen ever owned or even wore a Rolex Explorer II. It is unclear exactly how this rumor started, but it has been accepted as false within the collecting community for a long time. However, the 1655 reference is still referred to as the Steve McQueen, but it is now done as an intentionally quirky misnomer rather than to indicate he owned the watch. It is also called the Freccione (meaning big arrow in Italian). This nickname seems to have come around as an intended replacement after the McQueen myth was shot down, but it turned out that instead of replacing it, both nicknames stuck. Confusing but true." 
     "McQueen's Rolex had a 1,8xx,xxx serial number, which would date it to around 1968/69 (earlier incorrect serial number record tables would have dated it to 65/66). The 5512 reference is distinguished from its visually identical sibling the 5513, by having a certified chronometer movement, which meant it was more accurate and was the more expensive of the two at the time. Some have posited that he had more than one of these watches, and he is believed to have given an identical Submariner to his friend, stuntman, and fellow racer Bud Ekins"

The model Steve McQueen wore in real life, also known as the Steve McQueen Rolex, is the Rolex Submariner, REF. 5512.

 Description from auction press release:

The Heuer Monaco was recently re-released due to the popularity of Steve McQueen and is for sale at Tag Heuer watch dealers. The current Monaco is slightly different from the genuine Steve McQueen model of the late 60's-early 70's. The chronograph dial does not measure as long a duration as the original and the movement is different. The dials are also different colors. The original model (ref. 1133b) is one of the most collectable of all Heuer watches.

The first Monaco re-issue had the earliest dial but the re-issue was very limited. After this first re-issued series, Heuer released a series with a dial that met the demands of our time. It was not a re-issue, but a 2000 remake. They also did not bring back one of the most remarkable features: on the original watch, the crown (to wind the watch and direct the hands) was at the left side, the pushers on the right side. This feature has direct consequences for the calibre (the 'inside' of the watch, the movement), so that will be the reason for not bringing it back. And they did not use the old logo. (Thanks to Paul Dezentje for the info.)

The original watch that McQueen wore during the filming of Le Mans sold at auction for $799,500.

What type of motorcycle did Virgil Hilts (Steve McQueen) steal from a German soldier while trying to escape from the P.O.W. camp in "The Great Escape?"

The motorcycle McQueen used in The Great Escape was a 1961 Triumph TR6 Trophy Bird made to look like a wartime BMW.