VIAIR 400P-RV Automatic Portable Compressor (part 40047) review

The VIAIR 400P-RV Automatic / part 40047 is a 12V clamp-powered compressor kit organized around RV tire access: a trigger-operated inflation gun, two hose sections and angled/twist-on attachments. It is distinct from the 400P-AUTO / 40045, from the 400P-RVS / 40044 and from the newer 400P-RV EF / 40144. Their names overlap, but the manufacturer pages and part numbers describe different configurations. This is an assessment of the 40047 documents, not a claim of RV installation or tested fill time.

Reach and fittings are the package’s main distinction

VIAIR lists a 30-foot primary hose and a 30-foot extension, a gas-station-style trigger gun with a 160-PSI gauge, a 45-degree extended-reach chuck for dual rear wheels and a 90-degree twist-on chuck. The gun also has a bleeder valve, so the manual explains how to check and reduce pressure while the gun remains connected. The two hose lengths and extra attachments are aimed at tires that may be awkward to reach without crouching or moving the compressor as often. They do not mean the kit is effortless to route: confirm that the connectors are secure and that the intended hose path is clear before inflating.

The product page names a 275/80R22.5 tire and claims an 80-to-90-PSI increase in under three minutes. That is a manufacturer claim for a stated tire/pressure change, not a result we measured or a promise for another size, starting pressure, temperature or battery condition. VIAIR’s portable tire table lists the 40047 with a 35-inch maximum-tire reference, which does not align neatly with the model page’s named RV tire. Treat both as bounded manufacturer information, not a general compatibility guarantee, and ask the manufacturer about the exact tire/workload if it matters.

The gun is manually controlled; the switch protects the pump

The product page calls this model automatic and lists an automatic shutoff function. Its manual gives the important qualification: the operator starts the compressor, holds the gun trigger to inflate, then releases the trigger at the desired tire pressure and switches the compressor off when finished. The pump’s built-in pressure switch cuts off around 155 PSI and restarts below around 130 PSI to prevent over-pressure operation. That fixed cycling is not a user-entered tire target, so this review does not count the 40047 as a preset tire-pressure auto-stop inflator.

The gun’s gauge is listed as 160 PSI with a ±3% tolerance. The manual says airflow makes the gauge inaccurate while air is moving, and instructs the operator to release the trigger to check tire pressure. Pause at the tire’s recommended pressure, stay present and do not treat the pump’s maximum working pressure as a vehicle setting. The manual’s 33% duty rating at 100 PSI translates to a stated 20-minutes-on/40-minutes-off cycle at 72°F and 100 PSI; do not confuse it with the 450P-RV EF, which is a separate model advertised with a different duty rating.

Power remains a direct-battery job

The 40047 manual specifies 12V DC, 30 amps maximum current and a 40-amp fuse. VIAIR lists an eight-foot power lead and dual battery clamps, and the manual says to keep the vehicle engine running. There is no documented accessory-socket connection or cordless mode. Verify the vehicle circuit and the supplied fuse before choosing it, and plan where the compressor can sit upright in a ventilated place while the hose reaches the tires. The machine and connected fittings become hot during and immediately after use; the instructions warn against water, soft sand and unattended operation.

The 40047 page lists a 150-PSI compressor working maximum and 2.30 CFM at zero PSI. Neither number predicts the time for your particular RV tire. The included hose also has care limits: VIAIR warns that sunlight can make it brittle, says to store it when not in use, warns against contact with the hot compressor head and does not recommend it in freezing conditions. These issues matter when deciding whether the kit will live in a hot compartment, outdoors or in winter travel conditions.

Check the suffix and the included kit

The standard 400P-AUTO / 40045 has a trigger gun but a single 30-foot hose in its listed package; the 400P-RV / 40047 adds a second 30-foot section, a long-reach chuck and a 90-degree twist-on attachment. The separate 400P-RV EF / 40144 listing describes an Enhanced Flow update with an SAE power connection and 25-foot primary plus 20-foot extension hoses—45 feet total, rather than the two 30-foot sections listed for 40047. That revised package is a different part, not evidence of an upgrade to the 40047. A 400P-RVS / 40044 is another catalogued RV-related configuration. Check the model and part-number label rather than buying from a broad “400P” title.

VIAIR lists a three-piece tip kit and a Presta adapter in the 40047 package. Its page says the compressor does not work with a Presta bicycle valve unless that adapter is used. Still, the reviewed product page centers on RV tires and does not establish passenger-car or bicycle capacity. The finder therefore treats RV use as an editorial scenario rather than claiming that the pump fits every tire or that the visitor selected an RV-specific need.

Who should consider the 40047?

On paper, the 400P-RV fits an operator who needs direct 12V battery power, a trigger gun, extra hose reach and RV-oriented chucks, and who accepts manual pressure checks. It is a poor fit if you need a dash outlet, preset target shutoff, cordless use or a compact single-hose package. Before ordering, verify the exact 40047 version and the full hose/chuck kit, inspect the current manual, confirm the vehicle’s 12V connection and fuse requirements, and ask VIAIR to reconcile the tire-size figures for a specific application.

Sources checked 2026-10-28: VIAIR’s 400P-RV / 40047 product page, its 40047 manual, the portable tire-inflator table and the compressor comparison chart; the separate 400P-RV EF / 40144 listing was checked only to distinguish the later variant.