Are these sensors accurate in the 4 to 10 psi range? I'm thinking of installing them on a ATV
These are usually within 2-4 pai accuracy. Fplease check your wheel stem holes to be 8mm to match. Also for 3 wheel, you can look at SRTP690
What size (stem) holes do the sensors fit?
It uses 8mm stem holes
Is there a backlight so it can be seen at night?
yes, the features on display, are all lighted and clearly visable at night
Is the system connected to power from the motorcycle so that it is powered on and powered off by the bike, or do I need to separately power this unit on at each startup?
the sensors are powered by replaceable batterirs with about 1 year life. The main unit is powered with built-in rechargable battery. You will need to charge the battery via included USB cord about every 6-9 months. With motion sensor, it will turn on and off with the motion of the bike
Will the new stem fit wheels with either 8.3mm or 11.3mm?
Sorry, these units are for wheels up to 6mm (1/4") thick.
It appears that there is a temperature reading on the monitor as well as pressure. is that correct?
Correct. The display will show temperature as well as pressure on each tire. You can change the default setting on max and minimum pressure also maximum temperature.
When the battery goes dead do you need to replace the entire sensor?
there are 2 different types of battery used in this system. the Monitor uses a rechargeable battery that you will charge every 6-9 months. The sensors use 4 round watch battery with 3-year life span. After 3 years, you can change the batteries or purchase new sensors.
Will system read pressures before wheel movement?
yes, as soon as you set up the system, it will show your tire pressure and inner temperature. It is not dependent on the movement of the wheels.
Can I connect sensors to an IOS app on my phone rather than having to mount the display?
The systems with monitore are paired to the monitor. They are not using Bluetooth, but radio waves. therefore they cannot be used by the APP on your phone.
How long do the batteries in the sensors last? Are they easily changed?
The batteries last two to three years.