The Hummer H3 is a smaller, more compact version of the H2 Hummers and they are actually capable of pulling some light to moderate loads depending on a few different variables. The H2's surprised me when it came to their pulling power and even though the numbers weren't super high, they were quite repectable considering the size of the vehicle itself.
Overview of the Data For the Hummer H3's:
Engine Choices: The engine you had equipped in your H3 made quite a bit of difference when engine options were specified in the towing charts. H3's made in 2008, 2009 and 2010 did state in their charts that there was two different engine options: the 3.7L and 5.3L engines.
The 5.3L had significantly more capacity over models that used the 3.7L engine, 1,500 pounds according to the data from the owner's manuals.
Automatic VS Manual Transmissions: The H3's had the choice between a manual and automatic transmission throughout the life of the vehicle's history and it did affect the towing numbers significantly! H3's equipped with an automatic transmission had a 1,500 pound advantage in pulling power compared to models that used a manual transmission.
Towing Capacity: From 2006-2010, the towing capacity numbers for the H3 Hummers varied from around the 3,000 pound mark and went up to a 6,000 pound rating. Some of the smaller towing capacities were found on models with a manual transmission.
Models that had the smaller 3.7L engine had capacities the ranged from the low end, up to roughly 4,500 pounds and models equipped with the larger 5.3L engine and an automatic transmission had the highest tow ratings.
Some model years below will only have one towing chart posted and these charts apply to all H3 model years because the data was the same.
Be sure to read the H3's owner's manuals to get familiar with all of the towing related info that GM stated to be sure you have a thorough understanding of your H3's limits.
2009 & 2010 Models:
The 2009 and 2010 Hummer H3's had quite the towing capacity range, which started out at 2,900 pounds and went all the way up to 6,000 pounds, depending on a few things.
The 3.7L and 5.3L engines were the two options for the '09 and '10 H3's and another factor that came into play was manual vs automatic transmission options, which also affected the towing numbers.
As you can see from the chart below, the '09 and'10 H3's were divided into two models: the H3 and the H3T, which was the truck version that had the bed in the back, instead of having a fully enclosed cab area. The 3.7L engines ranged in capacity from 2,900-4,500 pounds and the 5.3L engines had a range of 5,900-6,000 pounds.
The 2008 H3's had a towing capacity range of 3,000-6,000 pounds, very similar to the '09 and '10 model years but the towing chart looked different and was more simplified.
The towing chart listed specs for the 3.7L engine and the 5.3L engine and then models equipped with a manual transmission.
The '08 H3's that had the 3.7L engine boasted a 4,500 pound rating and models equipped with the 5.3L engine had the higher 6,000 pound rating. The lowest specs were for models that had an automatic transmission equipped and from my research, I believe that these were only available for the 3.7L engines.
2006 & 2007 Models:
For the 2006 and 2007 model years, the Hummer H3's towing chart is broken down into two different towing specs and these are for automatic transmission models and manual transmission models.
The towing capacity for the 2006 and 2007 H3's was either 3,000 pounds or 4,500 pounds, depending on the transmission equipped.
What's The Difference Between The H3's And The H3T's?
The 2009 and 2010 H3's towing charts specified that there were two different models listed and this was either the H3 or the H3T.
The H3 is basically just an SUV type of body style where the entire cab is enclosed.
The H3T has a smaller truck bed in the back of the vehicle and a smaller enclosed cab area.
Resources For The Hummer H3's:
I gathered all of my towing information from GM's website and used the owner's manuals, which had all of the towing charts that I found and posted on this page. There is a ton of other information related to towing that I recommend you look at and is why I linked to the owner's manuals here.