What is steer axle weight limit drive axle weight limit trailer axle weight limit on a semi?

A general rule of thumb for a five axle unit conducting interstate travel is 80,000 lbs. gross, with a max of 34,000 per set of tandems (provided there is a bridge of at least 35 feet between the drive and trailer axles), and 12,000 lbs. on the steer axle. While it doesn't change what you can gross overall, a trailer with a ten foot spread axle is allowed 40,000 lbs. total on the trailer axles (but no more than 20,000 on each axle), and you can actually go up to 20,000 lbs. on your steer - IF you have an axle and tires rated for that kind of weight. Typically, only vocational trucks and heavy haulers do, while most highway trucks will run 285s or 295s on their steers, with a rating of 12,300 to 13,000 lbs.

For intrastate travel, several states have higher weight limits grandfathered in, and those weight limits will vary between those states, and will also be determined by wheelbase of the vehicle and whether it is traveling on primary or secondary roads.