Wheeler Lake ...
This is a relatively easy trail for modified vehicles when it is "dry". I use the term "dry" loosely since this trail is surrounded by springs and crisscrossed by small streams and trickles. You can expect to do 70% of this trail with soaking wet tires at the best of times. There is no real mud. This being Colorado its really just too sandy for mud. But, early spring and late fall will have enough snow to make up for the lack of mud. Tires that self-clean - eject the mud and slop - are essential as well as the ability to grip well while wet and cold. I should probably say right here that this is a BAD trail for Boggers or Thornbird style (i.e. badly designed A/T) tires. Boggers don't pack up bald but have NO lateral stability - you'll ski sideways off the first snow bank you hit - and Thornbirds will just pack up bald and leave you at the trial head.
The trail is pretty flat. Overall only a slight to moderate incline. No off camber to speak of. In fact, the only REAL incline is the last 3/4 mile of trail. You'll know when you get there.:-) The trail takes a jog to the north up the side of the ridge along a STEEP shelf trail covered in rocks up to the size of beach balls, with a stream running down the middle. The trail switchbacks several times before you reach the shelf at the top. BEWARE! There are only one or two passing/turn-around place between the bottom and the top and those are nominal. The trail is very narrow and very steep! About half way up the ridge the trail makes a 160 degree turn into the "crack". It is possible to do this without locking differentials and a winch but its certainly easier and less potentially damaging to your body work to have lockers and or a winch.
There are several really fun obstacles before you reach Bowling Ball Hill. Each has a nominal easier route for those less adventurously inclined. Any of the routes, however, involve climbing slick, polished, sand covered granite with wet and probably muddy tires. Your vehicle will slip so don't forget to take that into account when trying to negotiate these obstacles. Rock skids and good skid plates will minimize vehicle damage.
One "mud hole" sits across the trail close to Bowling Ball hill. Our last couple trips have seen it mostly empty. However, when full be aware that the hole can easily be three to four+ feet deep. Thankfully the bottom is pretty solid but it is sprinkled with a liberal amount of pointy differential, transmission and oil pan eating rocks. None of which you will be able to see if theres more then a couple feet of water. There is no way around this obstacle - please DO NOT try to make one - and if you can't make it through here then you probably won't be able to make it up Bowling Ball Hill.
Another thing to mention is the altitude. Starting at about 11,000 feet in elevation and ending at about 12,700 the trail is only about 3.5 miles long. Doesn't sound too bad but carborated vehicles are usually challenged. Most of the obstacles are steep single or multiple rock steps or Vs that put your vehicle at extreme inclines and angles and tend to bounce it around a lot. Enough to drive carburetors crazy.
Last thing, I swear.:-) While I HAVE seen stock vehicles negotiate this trail the last was several years ago and the trails has since gotten somewhat more difficult. This entire trail is covered in loose rocks from the size of cantaloupes to basketballs+ and they tend to jump out of nowhere to whack things under your vehicle - hence, how its earned the name "Mexican Jumping Rock Road" from us. The obstacles are steep, jagged and slippery and there is very little room to maneuver a long wheelbase vehicle. Most of the trail is perpetually wet. Some parts of the trail have no bypasses or places to turn around, meaning you may have to back up a significant distance. And in several places on the trail there is no room to negotiate around beach ball and basketball sized rocks - you have no choice but to drive over them. Stock vehicles with long wheel bases (i.e. pickups, SUVs) street tires and stock ground clearance are just asking for serious body and undercarriage damage on this trail. (BTW, did I mention all the willows that'll scratch the paint off your new truck?) Consider 31x10.5x15 All Terrain tires the minimum for this trail - 33x12.5x15 sticky Mud Terrains would be best. A decent amount of ground clearance or really good skid plates. VERY good approach and departure angles. The lower the vehicle sits and/or the more overhang the more important these are. (See the 2002 pictures to see what I'm talking about. Both black Sports have more then 25 inches of clearance from the ground to the rear bumper.) Lastly, open differential vehicles will need very good articulation and tires to negotiate some of the obstacles without a locking differential(s) or winch.