Speed error
#1
Driver School Candidate
Thread Starter
Join Date: Sep 2004
Location: California
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Was wondering if anyone has notice that there speed is off. I have a 450H and have noticed that the speed is about 2-2.5 off per radar speed signs and my Garmin gps
#2
#6
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
This is tricky. There are a lot of things that could contribute to the slight discrepency (tire pressure and size, instantaneous reading, etc.). Also, the radar has to be tuned correctly to give an accurate reading, and I suspect there's not a great deal of effort in that respect for those speed signs that get drogged around or can sit for days. I think that's why police give a few mph cushion before grabbing someone for speeding. Does your Garmin agree with the radar reading?
Last edited by ziggy1; 06-01-10 at 06:19 AM. Reason: clarity (i hope)
#7
Lexus Test Driver
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
If I compare mine to the radar, I am actually going 1-1.5 mph slower than the radar says. I like the fact that it does that. I feel safer when I come up on photo radar.
Of course I have no idea how accurate the radar is. It's a permanent sign and they just replaced it with a new one, so I'm thinking pretty dead on.
Of course I have no idea how accurate the radar is. It's a permanent sign and they just replaced it with a new one, so I'm thinking pretty dead on.
Trending Topics
#8
Driver School Candidate
Thread Starter
Join Date: Sep 2004
Location: California
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Garmin and radar are pretty close. I think that the milage is close, will check that later. It is not a big deal was just wondering if others had noticed it.
#9
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
I've noticed it as well with my 2010 RX 450h. Speedometer is 1-2 mph lower than my Garmin GPS and the speed-radar signs. FYI, I have the 19" wheels, and thought it might be due to that. Not a big deal, but I wonder if the total odometer mileage is also effected.
#10
Moderator
![](https://www.clublexus.com/forums/images/ranks/rank-mod2.gif)
Join Date: Aug 2006
Location: San Francisco, CA
Posts: 12,054
Likes: 0
Received 74 Likes
on
45 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
yep, my 2004 is the same thing. I am actually going faster than what the radars say. As in, if it says im going 35, im actually going 37 ish according to the speedo. I dont think car makers change the speedo in regards to tire size options
#11
Lead Lap
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
another question would be do the owners with 18" wheels have the same problem? then if not, compare the overall diameter of the 19" wheel & tires to that of the 18" wheels.
size of wheel doesn't really matter in this scenario as it's the combination of wheel and tire that determine the overall diameter.
size of wheel doesn't really matter in this scenario as it's the combination of wheel and tire that determine the overall diameter.
#12
Pole Position
Join Date: Jun 2007
Location: Sunny Prestwick in Avon, IN
Posts: 283
Received 0 Likes
on
0 Posts
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Hmmm.... I did notice it a couple weeks ago. I was traveling 75 and it showed up some place I was going 73. I checked it several times on a trip to and from Michigan (from Indy) and noticed it both directions. Now I set the cruise to 77 when I want to go 75. I have the 19" tires as well and did process that too.
lar
lar
#14
Lexus Test Driver
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
If I compare mine to the radar, I am actually going 1-1.5 mph slower than the radar says. I like the fact that it does that. I feel safer when I come up on photo radar.
Of course I have no idea how accurate the radar is. It's a permanent sign and they just replaced it with a new one, so I'm thinking pretty dead on.
Of course I have no idea how accurate the radar is. It's a permanent sign and they just replaced it with a new one, so I'm thinking pretty dead on.
My head hurts after that one.
#15
![Default](https://www.clublexus.com/forums/images/icons/icon1.gif)
Yes this is normal for all cars google it. This has been done to keep you under the speed limit. The cars always tell you you going faster then you really are, this way if the cop radars you over the speed limit you can't say my speedo must be off. The tolerances are not close enough and there is to many variables (to make the speedo 100% exact) so the car manufactures just makes sure it reads a few % faster so they are covered from any border line lawsuits.
Thread
Thread Starter
Forum
Replies
Last Post