Basketball hoop on a sloped driveway: level the anchor, not the driveway

What slope does to a hoop

A driveway that drops 3 inches over the 4-foot depth of a portable base tilts that base about 3.5 degrees, which puts the rim a few inches out of level side to side or front to back and leans a 10-foot pole so that every gust and every rebound pushes it downhill. On an in-ground, a pole set to follow the slab would do the same, which is why no manual sets the pole to the slab: the Silverback manual has you level and square the anchor plate in the wet concrete with a level, and then plumb the pole on day 5 with the leveling nuts. The slope becomes the driveway's problem, not the hoop's.

In-ground on a slope: the anchor does the work

1. Set the concrete form so the top of the footing is level and at the court's surface at that spot; on a slope one edge of the form will stand proud of the slab and the other flush. Goalrilla's guide and the Silverback manual both call for a form on the top 4 inches.
2. Push the anchor into the wet concrete and level the plate with a torpedo level on two axes; square it to the court, not to the slope line.
3. On day 5, stand the pole on the bolts with the bottom leveling nuts backed up evenly, strap a post level to two faces, and turn the nuts until both vials read plumb. The Silverback manual's step 14 covers the nuts; this is what they are for.
4. Grout or mortar under the base plate if the manual calls for it, and slope the finished concrete away from the pole so water does not sit at the ground line.

Portable on a slope: shim, ballast, anchor

No maker we read publishes a slope rating for its portables, so what follows is the practical order of fixes, cheapest first. Shim the low side. Pressure-treated lumber or composite shims under the downhill edge of the base until a level on the base reads flat; cut them to the base's full width so the plastic is supported, not point-loaded. Fill with sand. Heavier than water and it does not slosh downhill. Add a weight bag. Silverback's holds 100 lb of sand on top of most bases. Point it uphill. A hoop facing up the slope sends misses back toward the house and puts the base's wheels on the low side, which is the stable orientation. Anchor it. A semi-portable that ships with cement anchors (Lifetime's 90734 Mammoth) can be bolted to the slab on its shims and stops being a portable at all. Wind and tipping has the ballast numbers.

Where 10 feet is measured on a slope

From the playing surface directly under the rim. On a sloped driveway the rim is 10 feet above the slab at the basket and a few inches more or less at the free-throw line, which is how every sloped driveway court works and not worth fighting. Set the height at the rim, check it with a tape from the front of the rim to the pavement below it, and shoot.

When to change the plan

If the slope across a portable's base is more than about 2 inches, shims start to be a platform, and a platform under a 300-lb base on a slope is its own hazard. That is the point to consider an in-ground beside the slab, where the slope is irrelevant, or a semi-portable bolted down. It is also worth measuring where the free-throw line lands on the slope; a court that is 15 feet long on a hill plays uphill from the line, and some families find the flat pad behind the house is the better court. In-ground vs portable covers the switch.