Let me tell you, when you’re behind the wheel of a massive RV, knowing exactly how fast you’re going is crucial. I learned that lesson the hard way when I first started RVing and got pulled over for speeding. Turns out my RV’s speedometer was off by almost 10 mph! Ever since that, I’ve become obsessed with finding the most accurate speed readout possible in my home on wheels.
After testing many GPS apps, I’ve discovered a few key factors that impact precision when it comes to speed measurement in RVs.
Wheel Size Matters
The foundation of any accurate speed reading is inputting the correct wheel size into your app settings. Unlike cars, RV wheel diameters can vary greatly depending on the type and size of motorhome. For instance, my Class C RV has 19.5″ wheels, while a big Class A can have massive 24.5″ wheels.
Small variations in wheel size can throw off your speed readout by as much as 4-5 mph! That’s the difference between obeying the speed limit and getting pulled over with a ticket. Most GPS apps will let you input your exact wheel diameter to ensure the speed calculation is spot on.
Be sure to actually measure your wheels or lookup your RV’s specs instead of guessing. And remember to recheck your settings if you change vehicles or tires. Consider it a basic maintenance task like checking tire pressure before a trip. Get that wheel size dialed in, and your speed readout will be smooth sailing.
GPS and Connected Data
At their core, most GPS apps determine your speed using satellite data. The more satellites your device can connect to, the more accurate the speed measurement. But GPS alone can sometimes fall short in rugged terrain like mountains and canyons where satellite connections sporadically drop.
Many apps compensate for this by incorporating supplemental data from your phone’s accelerometer, compass, gyroscope, and cell tower connections. The fusion of GPS and motion-based data delivers speed estimates accurate to within 0.1 mph.
Apps like AllTrails go the extra mile by crowd-sourcing data from other users to determine average speeds on specific routes. Having additional data sources to cross-reference makes their speed readouts incredibly reliable, though coverage may be lacking on more obscure routes.
Bottom line – the more data streams available to compare, the better! I always look for GPS apps using both satellites and phone sensors to remove any gaps in coverage.
Offline Maps
As any experienced RVer knows, cell service and data can be sporadic at best when traveling off the beaten path. Nothing kills your speed readout quicker than losing internet connectivity out in the boonies!
Some GPS apps get around this by offering offline maps that store road data directly on your device. Apps like CoPilot provide detailed offline maps encompassing all of North America, so you stay on course even when service cuts out.
The tradeoff is that offline-based speeds rely solely on GPS, minus the supplementary data that boosts precision. Readouts may be spottier, but at least you get something!
I always download offline maps before a big trip as an insurance policy against connectivity issues. Even if speeds are less accurate without data, at least I can still navigate and avoid speed trap tickets!
Calibration Drives
Of course, you can have the perfect app setup and still get misleading speed readouts if your phone’s hardware is out of whack. Tiny variations in accelerometer and GPS hardware calibrations can throw readings off. But there’s an easy fix – calibration drives!
Before a long trip, I take my RV on a 10+ mile drive on a highway with a well-marked speed limit I can follow precisely. Using my app of choice, I compare the readout speed to the actual posted speed to see any discrepancy.
If it’s off by 1-2 mph consistently, I can just make a mental note to adjust my driving accordingly. Or some apps actually let you calibrate and apply an offset. Just like that, your readings are dialed in!
It takes a bit of diligence, but running calibration drives gives me peace of mind that my RV speed is spot-on. And it only takes a few minutes – a small time investment to avoid speeding tickets!
Dash Mounts
Mounting your phone securely while driving is important in any vehicle, but especially so in an RV where things tend to rattle and bounce around over uneven terrain. Even the slightest phone movement can throw off speed and acceleration details used to calculate your readout.
Most GPS apps recommend locking your device into a dash mount or windshield cradle rather than sitting it on your console or seat. This prevents the inevitable sliding and bobbing that can skew speed data.
You’d be amazed what a difference solidly mounting your phone can make. After getting a heavy-duty dash mount, my speed readings became way more consistent over bumpy backroads. Do yourself a favor and invest in a sturdy mount – it’s a cheap upgrade for better accuracy.
Speed Optimized Devices
At the end of the day, the device you use can have just as much impact on speed readout as the app itself. Most modern smartphones have GPS hardware optimized for navigation accuracy rather than speed precision.
If hyper-accurate RV speed is your top priority, consider getting a dedicated GPS device designed specifically for speed measurement. Brands like Racelogic make compact in-vehicle systems using dual antennas to provide professional-grade speed readouts within 0.1 mph.
Of course, this level of precision comes at a hefty price – expect to pay $1200+ for pro systems compared to a free app download. Then again, avoiding just one speeding ticket may offset the cost!
For most RVers, a smartphone GPS app works fine with proper setup and calibration. But gear heads obsessed with accuracy may want to investigate high-end options.
Find Your Flow
As you can see, getting an accurate speed readout in an RV requires some extra consideration compared to a car. Between wheel size, data sources, offline maps, calibration, mounts, and hardware, there are a lot of variables at play. Don’t worry though – a few simple tweaks goes a long way.
Here are my top app picks that nail the basics for most RVers:
- CoPilot GPS – Offline maps and basic accuracy
- AllTrails – Crowd-sourced data for precision
- Navigon GPS – Wheel size customization
Do a short calibration drive before each trip, keep your phone locked in a mount, and you’ll be cruising confidently at legal speeds in no time. Never underestimate the importance of an accurate speed readout in a rig – it saves headaches and tickets!
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