VIAIR 400P EF RV Digital Compressor (part 40244) review

The VIAIR 400P EF RV Digital is the 12-volt, preset-stop RV variant identified by part 40244. It is one selection on a shared page, not a package containing both the 400P and 450P compressors. The manual separately names standard 40243 and RV 40244; the latter adds a second hose and dually-specific reach attachment, while keeping digital target control rather than the hand-trigger system used by EF Automatic models.

What the RV kit changes

The 40244 is laid out for a tow vehicle and an RV or other multi-axle arrangement. Its manual describes a primary and extension hose for up to 50 feet of combined reach, plus a 45-degree dually-specific chuck for inner dual wheels on motorhomes, trailers and dually trucks. The page’s specification list, however, labels the hoses as 25 feet and 20 feet. Those component lengths total 45 feet, while page copy and the manual say 50 feet of reach. The sources do not explain the difference. Treat the longer figure as a reach claim, not a measured length of hose, and ask what the exact seller package includes if placement depends on every foot.

The 45-degree dually chuck has an open-end, push-on design and does not lock to the tire valve. The manual directs the user to stay at the wheel and hold it against the valve. It can help with inner-dual access, but it is not a hands-free attachment; the standard clip/lock-on chuck is listed separately.

Digital target stopping, with an attended setup

“Digital” describes a meaningful control difference here. The manual shows the operator selecting a target on the pressure display and pressing Start/Stop; it says the compressor runs and stops automatically when the selected target is reached. That is not the same as the fixed pressure-protection switch in a manually controlled compressor, and it is not the trigger-only operation of a 400P-RV EF Automatic. A preset stop can reduce the need to hold a trigger at the wheel, but the manual still says not to leave the compressor unsupervised. Watch the connection, check the finished pressure with a suitable gauge and use the vehicle placard or owner manual’s cold-tire target—not the tire sidewall maximum.

The manual recommends keeping the vehicle running during use to help maintain system voltage and avoid draining the battery during extended inflation. The reviewed 40244 package is described as a direct-battery setup through a two-pin SAE lead and clamps, not a dashboard-socket unit. VIAIR lists a maximum draw of 30 amps and 87.3 amps of inrush at zero PSI, alongside a 40-amp inline fuse holder. These are different electrical figures: the fuse is not the pump’s normal maximum draw, and the zero-pressure inrush is not a continuous-current rating. Compare the specified clamp route and fuse instructions with the vehicle and pump manuals before connecting.

Duty and the manufacturer’s stated examples

VIAIR lists 100% duty at 40 PSI and 30% at 100 PSI for this model, with 150 PSI as its maximum working-pressure figure. Read the pressure-specific duty points together; “100%” at the lower pressure does not mean the same schedule at a higher RV-tire pressure. The maximum working pressure is a compressor limit, not a sensible inflation target by itself.

The page also presents named fill-rate examples rather than one universal speed promise. It lists a 35 x 12.5 R15 tire from 0 to 40 PSI in 6 minutes 25 seconds, a 37 x 12.5 R15 from 0 to 40 in 7 minutes 15 seconds, and an RV-size 245/70R19.5 from 60 to 80 PSI in 1 minute 39 seconds, each with a stated tolerance. These are VIAIR’s reported cases, not independent measurements, and they do not predict a different tire, ambient condition, battery or starting pressure. In the same named 245/70R19.5 window, the 450P EF RV Digital / 45257 table gives 2:02 ±10 seconds; that one comparison does not make the 40244 universally faster or more appropriate. The 450 has a different duty rating and electrical profile.

Physical and setup checks

The manufacturer lists a 12.44 x 6.69 x 7.57-inch body, 10.75-pound weight, IP54 and a -40°F to 158°F ambient range. The manual warns about a hot head, calls for ventilation and a stable surface, and says to install the air filter before operation.

The exact-model image identifies the 40244 compressor, not a seller's complete kit. Confirm the clamps, both hoses, dually attachment and bag; the reviewed page/manual do not establish a supplied Presta adapter, ball needle or seven-way lead. The family manual says the seven-way connector is sold separately.

Who should compare it

Compare the 40244 when preset stopping, direct battery power and dually reach fit an RV / tow-vehicle workflow. It is lighter than the 45257, but its duty rating falls to 30% at 100 PSI and its 30-amp maximum draw deserves an electrical check. The 450P EF RV Digital has a 100%-at-100-PSI claim and lower maximum draw, but its fuse discrepancy needs current documentation. This review does not establish passenger-car-only, bicycle-valve or outlet-powered use for 40244.

Before using or buying it, obtain the current part-specific instructions, verify the fuse and power arrangement, confirm the hose and attachment package, and check whether the intended wheel can be reached safely. No product was purchased or operated for this assessment, and the manufacturer’s timing examples are not our tests.