Officially, only the trailer manufacturer or a certified vehicle modifier have the authority to increase it’s GVWR.
However, replacing your tires with some that have more load capacity is always a desirable option. Properly inflated they will provide much needed reserve load capacity.
Make of trailer is in my signature, not sure on rating of axles. Airdale answered what I was suspecting. Going up a load range definitely helped with the way it towed plus the tires don't look like a squished donut. Thanks for both of your replies. Take care.
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2012 F350 Lariat CC SRW 6.7L Powerstroke