Speedometer and cruise speed don't match

Has anyone had an issue with their speedometer and cruise control speeds not matching when the cruise control is activated? My 2019 Tundra TRD Off Road has consistently displayed my speed at 1mph less than what the cruise control speed is set at. It's probably not an issue to most people, but my OCD causes it to bug the heck out of me! I thought that maybe the all terrain tires could be causing it, but they are the stock tires that came on the truck and I haven't done any modifications. The only time the speedometer and cruise control speeds match is when I go down a hill. Any ideas on what could be causing this? The truck only has 2700 miles on it so it's still under warranty.

 

Your truck is obviously defective. You should trade it in for a Ram immediately.
Just kidding, don’t do that. Mine does the same thing. I’m not sure but I think maybe it has something to do with the way the ECU rounds the speed up or down. I choose not to worry about it.

 

The cruise control set speed is the target the CC system tries to achieve.

Through real world conditions your truck will never hit that speed, and maintain it consistently. There are variations.

Road conditions, wind resistance, temperature, and more.

There is no issue with your truck, and odds are there is no "fix." The reality is that we all drive in a "real world" setting where variables are constantly changing. This causes fluctuations in your actual speed reflected by your speedometer. Your CC system will do whats necessary to maintain that speed as close as possible.

1 MPH difference on speedo vs set speed just means that your trucks cruise control system is healthy, and operating correctly.

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Might also be your Cruise control distance pacing radar slowing you down slightly. You can turn it off by holding in the cruise control on/off button for a few seconds when you turn on Cruise control and that will set your cruise without the distance pacing radar. Try this and see if the issue still exists.

 

Forgot about the radar cruise with my "unadvanced" 2002

 

Interesting! My 2019 does the opposite, 1 mph faster in cruise than the set speed with zero mods. This is my first Toyota and found it odd they couldn't hit the mark on a flat road. I just set my speed 1 mph lower than where I want to cruise and let it go. I'm more pissed about the downshift strategy; the tiniest little hill will cause a 6->5 downshift with minimal payload. Could be worse though, the gov't could regulate those squishy humans out of the driver seat.

Edit: post your tire size when you get a chance. Mine is P275/65R18. I wonder if the tires offered are 'close enough' instead of accounting for tire size in vehicle speed calculations.

No clue why there's a difference. Online wheel/tire size calculator shows 629 revs/mile for both 275/65R18 and 255/70R18.

 

My truck displays actual speed at 1 mph lower than cruise target. Bothers my OCD as well. I set cruise for 1 mph higher than my intended speed and more often than not it will match that speed perfectly. I was convinced my truck was doing that on purpose just to get under my skin.

 

One my 2020 my cruise control is spot on. It reads exactly the same as the set speed. There is something definitely wrong with your truck and I would take it in and raise hell.

 

Yeah, I noticed this in my 2020 with all stock wheels/tires. It is not 100% consistent though. Sometimes they match, sometimes they don't. When they don't, the cruise target is always 1 mph higher than the speedometer on flat ground. And I ALWAYS use the "Constant Speed" cruise control. I hate that radar crap. I don't like it, but my OCD is not sever enough for it to do more than irk me a little.

 

Thank you all for the responses. My Tire size is P255/70R18. I don't use the radar cruise. My issue is only with the regular cruise control.

 

Picked up truck on Saturday. Drove it 130 miles back home and noticed it was always 1mph lower on flat when using cruise control (radar control).
20" wheels, no TRD offroad

 

Mine is hit and miss. If on digital speedometer it will be right on or 1 mph off. But the actual speedometer needle always says what the cc is set too. Half the time i set the speedometer when the digital speed is what I want and it sets no problem.

 

I hate the whole idea with TSS, especially the dynamic cruise control.

 

depends on when you hit the button to activate the set speed. sometimes i can get it to set at 75 and show actual 74 and at times set it at 75 and actual be 75. it really depends on if you set it at actual 74.x+ or 75.x+

i think the display is just rounding set and actual down/up depending on actual speed vs set display.

 

I noticed this one time I used cruise control but other times it's been bang on. I don't use cruise often enough to detect a pattern.

 

My 2017 Camry does the same thing.

 

I had to make a run to Tallahassee this morning. Used my Garmin so I could compare speeds. With my cruise control set at 78, the analog speedometer read 78, the digital speedometer read 77 and the Garmin said 76. This is the eighth Toyota I’ve owned. They have all been a couple mph’s slow at similar speeds.

 

Mine is always 100% spot on (at least on flat ground!).

 

New here. Just curious as to if anyone has an issue with the digital speed and the actual needle on the speedometer not matching about 4mph difference. To make it worse for OCD is that the GPS speed on the phone is lower than both...how can I know how fast I'm actually going. Cruise control seems to agree with the digital speed (didn't compare to GPS because my phone died).

 

Based on the speeding ticket I got, I'm pretty sure my digital speed display is accurate. That was surprising to me as I'm pretty sure the speedos in all my other cars read 2 kph high. I never look at the analogue gauge because I can't see it very well with how I have the steering wheel set.

 

You got a speeding ticket? What kind of lawless scruffian are you? JK Rosy, have a great day!

 

You got me!

Turns out the city put a speed camera at the spot on my previous commute where you come down from the "hill" of the freeway overpass then go up the "hill" for the railyard overpass. So I was trying to maintain momentum for good fuel economy. I was also the slowest guy through that area before they put the camera in. Every single person I've talked to who drives there got a ticket at that spot but the traffic coming off the freeway does so at a much more reasonable speed now.

 

I changed my “home” display to not be the digital speedometer... so I don’t notice the discrepancy.

 

There's a pretty decent chance your speedometer is off by a little bit too. Check it with a GPS and then your OCD can really kick in. Or, you can just drive it and enjoy it without worrying about it.

 

My ‘21 does the same thing - 1 mph lower than setting. And it’s not the related to the radar cruise. I usually turn that off and use constant speed cruise.

 

I just got back from a trip from Colorado to Idaho and went the Teton mountain route. The only way I found my cruise stays on the set speed is after it’s gone through a few hills and shifting points. Once it found the sweet spot it stayed dead on the rest of the way. Also have 315/70 on a 3” lift.

 

My 2020 does it too. Very annoying. In general, the entire cruise control system (including the DCC) on the Tundra just sucks. My other cars are a 2019 Chevy Impala and a 2018 Honda Accord, both with DCC. Their systems are far and away better than what's in the Toyota. Particularly on the Impala, the DCC works wonderfully. Whereas, on the Tundra, it is jerky and slow to react. GM and Honda just did a way better job with their DCC systems.

 

My 19' CM digital speed matches the cruise set speed # , I have compared speed with a GPS phone app and my truck reads about 3-4 kph slower than what the GPS says I'm actually doing . Moving up to a 33" tire should solve my speed discrepancy