thanks for clearing that up.

No, I did not do the GPS test on the car with the original tires. (and I don't feel like putting the original tires back on for a test... )

If there is anyone in the South San Jose Ca. area with a 06/07 Civic Hybrid with the original wheel tire combination who would like to help with this test, please email or PM me.

I suspect that given the speedometer reading with the new tires is dead on the GPS data, that the OEM tires would be a little slower because those tires are taller.

 

Click here to see the specifications of each tire size. The revs per mile are within 4 of each other.

For all practical purposes, the 2 wheel/tire combinations are 99.5221027479% identical to each other!

So now Hybrid owners have a choice, the pie pan nerd look, or the hip and cool look!

 

380 vs. 640 on the treadwear, too! You better like those tires for quite a while!

Tirerack is a great resource for good info like this. 1/10 of an inch less results in 4 more revs per mile. Surely this equates to almost nil in the speedometer readings between the two tires.

Do you find traction and handling any better? Typically, wider & lower profile tires (which the 16s are) improve handling somewhat. Your 16s have 1 inch more tire-patch to the road. Downside is usually slightly less MPG.

I like the look of the EX rims and tires, although I'm starting to like the pie-tins too. (What is wrong with me? ).

 

When there's no GPS signal, the car can do dead reckoning using the speed sensor and a yaw meter. So it wouldn't really make sense to give you the GPS reading on the speedometer, knowing that sometimes that info is faked. Besides, they'd just have to design a different version so the non-GPS models would have a reading.

Somebody correct me if I'm wrong, but didn't I see a setting in the GPS configuration that would let you set your tire size?

 

If you Turn the Standard radio with the 1 and 6 buttons depressed, The radio enters daignostic mode,
Now press 5 and the readout will be the vehicle speed, turn radio off to return to normal


Interestingly this mode is sopt on with my GPS, and 3 Kilometers under the Speedo. Go Figure.

 

Correct. When I go through a tunnel the GPS still tracks me on the road and will even show a lane-change if I do such a move as it is basing it on Yaw rate and Vehicle speed. If someone in Europe can test this further as you folks have those 8-mile long tunnels with off-ramps and merges and things. =)

Also, in the "behind-the-scenes" screens in the Nav system there is a page for Yaw Rate and "Tire Calibrate." At the time I took the photo of the screen my readings are shown below though I think this was while parked so others might have other readings.

Yaw Rate:

• Sensor = 2.479V
• Offset = 2.481V
• CCW (Counter-clockwise) Factor = 0.1%
• CW (Clockwise) Factor = -0.8%

Tire Calibrate:

• Auto Tuning = On
• Study = Level -531
• Tire-Calibrate Tuning = 0.56%

When you are on the Yaw Rate screen and choose the Tuning button this brings up a screen (more fun when you are driving) and when you turn the steering wheel you can see the visual change on the screen and setting the numbers higher make a larger change in the display when you turn the wheel (I think - always hard to concentrate on these settings while driving). Maybe if you put on 12" tires or some mud-bogging 20" tires you can set these screens to have an accurate speedo readout.

 

Would you write up the key sequence for the Nav system radio to go into the service/maintenance mode?

 

This should be a Sticky somewhere. To get to the initial screen you hold down Cancel+Menu+Map for 3 seconds. This brings up a screen titled "Select Diagnosis Items." On this page you will find my favorite screen for "GPS Information" if you click on GPS Info it shows a real-time readout of elevation and the satellites it is tracking and this prevents you from having to tap the map each time to see your elevation, but I digress. On this page though there are buttons for Yaw Rate and Tire Calibrate.

What's more fun though is on this main screen you hold down (I think) Menu for 3 seconds and it reveals a screen titled "for Developer." This has 13 options on it and let you change the Map Color, Voice pitch, Brightness settings, etc. Many settings (if not all) are reset when you shut off your car though. If you start the car, get to the setting for Voice pitch/speed, then it stays there until you turn off or restart the car, IIRC.

I can upload all these photos but there are about 30 of them showing a snapshot of basically each screen. Give a shout if some of you want to see these pics.

 

Something to try tomorrow!

I wonder if there is a screen that shows coordinates, elevation, bearing and velocity?

 

The tire calibration isnt something that you should mess with.

from the service manual:

as the vehicle moves the navigation system recieves speed pulses from the PCM. These pulses are converted using a conversion factor to a MPH speed that moves the vehicle position (VP) on the map. The navigation system has an internal tuning function that generates and refines this factor based on actual driving. The "level" indicates the status of the tuning.

• the auto tuning is factory set to on, and should remain on
• The study indicates tuning status
• the tire-cal. tuning and set SHOULD NOT BE USED it is for factory use only.

the yaw meter works in conjunction with the solar angle to determine air conditioning loads on the drivers side vs the passenger side of the car.