One of the most practical questions we help customers answer every day: What size space do I actually need? Getting this wrong costs you — either you pay for more than you need, or you end up with a unit that's too tight to maneuver comfortably. Here's a practical guide.
How to Measure Your Vehicle
Before you call any storage facility, measure your vehicle's total length including tongue or hitch, maximum width (including mirrors for motorhomes), and height at the tallest point (roof vents, A/C units, antennas). These three numbers determine your unit.
Matching Vehicle Type to Unit Size
Boats on Trailers
- Bass boats, small fishing boats (14–18 ft): A 10×20 or 12×25 space typically works. Measure your trailer length from hitch to tail.
- Mid-size boats (18–24 ft): A 12×30 space fits most with comfortable room.
- Large pontoons, ski boats (24–28 ft): 12×30 to 12×40 depending on trailer setup.
- Large bowriders and cabin cruisers: 12×40 or larger. Call us with your exact trailer length.
Travel Trailers
- Small travel trailers (18–22 ft): A 12×25 or 12×30 unit handles these comfortably.
- Mid-size trailers (22–28 ft): 12×30 is the standard fit.
- Larger trailers and toy haulers (28–40 ft): 12×40 or larger recommended.
Fifth Wheels
- Fifth wheels tend to be taller than travel trailers — verify height clearance at covered bays.
- Most fifth wheels run 35–42 ft. A 12×40 handles most; longer ones need 12×45 or bigger.
Class A, B, and C Motorhomes
- Class B/C (20–30 ft): A 12×30 unit typically fits well.
- Class A (30–40 ft): 12×40 to 12×45 depending on exact length.
- Large Class A diesel pushers (40–45 ft): Big River's 16×53 covered bays, arriving as part of the Eureka expansion in 2026, are designed for these — one of the largest covered options in St. Louis County.
Always Add a Little Buffer
Don't try to cram a 30-foot trailer into a 30-foot space. Give yourself at least 2–3 feet of extra length for the hitch or tow vehicle clearance, and 1–2 feet of width on each side. Storage is a tight environment — extra room makes a real difference in how easy it is to get in and out each visit.
Not sure what size you need? Call us at (636) 441-9888 and tell us your vehicle's make, model, and year. We'll tell you exactly which unit size works best and whether we have it available.
View all available unit sizes across Big River's three St. Louis locations →
