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Cbatoday

Cold weather and tmps

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Has any one else got the low pressure warning today as the temp over night dropped. The technical guy at toyota said this would happen 

Cant be much of a percentage between being ok and being to low

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Around 20-25% normally, though temperature changes can still prompt tmps warnngs until temperatures stabilise.

See 

 

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Cold weather makes tires lose pressure, i already inflated mine 2x as there was a sharper drop.

You should go to your local station and inflate them to required pressure, open driver door, there is a label on the pillar showing how much to inflate them too.

If you have deflated tires, your mpg suffers, so does your handling.

 

 

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Thus far, despite the witches promise from the dealer, I haven't had the warning come up. Temperature when pressures were set (after I discovered the dealer hadn't bothered to check them and they were still at the 50+psi they came with from the factory 🙄) was around 14C.  Lowest so fare has been -2C.  It may be that with the 18" 40 profile tyres and relatively low pressures the risk is less than with the higher profile tyres (which run at at higher pressure to start and have a greater volume) on the 16" and 17" rims may suffer more.

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Yup. I got a warning as I left the car park at work tonight. That's a bit naff. I never got a warning from my previous Jazz in cold weather.

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Checked my tyres this morning and they were at 32 psi instead of 35psi so cold weather caused a 3 psi drop. Wouldnt have thought a 10% difference would have caused the light to come on.

I put them back to 35 psi but... if the temp increase this will increase the pressure to 38 psi. Would this again put the warning light on or is it only if the pressure drops rather than rises.

Also does the monitor come on at a set psi or a drop of a certain percentage

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My last Prius was my first car with the built-in TPWS, and the light came on when the weather turned below about 7°C.  The pressure had dropped from 35 psi to 32 psi.  I had my winter tyres put on by my dealer the next day, and I got them to inflate 2 psi above recommended pressure as it was a warmer day and temperatures were likely to fall further.

According to my RAV4 manual, it primarily mentions the light coming on due to pressure falling in one or more tyres.  However, in quite a long list of "Situations in which the tire pressure warning system may not operate properly" is this one:

  • "If the tire inflation pressure is extremely higher than the specified level."

Surprisingly, it also says "When tire inflation pressure declines rapidly for example when a tire has burst, the warning may not function".

I have an aftermarket TPMS which comprises 5 radio transmitting dust caps and a receiver on the dash that displays the pressure in each tyre, and at the press of a button their temperatures (as transmitted down the brass core of the valve stem).  This will raise an alarm if any tyre falls below or above a specified pressure, and also if the temperature exceeds a preset value.

Since getting the device, I've had 2 slow punctures and both times my 3rd party system warned me sooner than the built-in TPWS.

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Good to know. Do you have a link to the system you purchased

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The Jazz had the simpler relative rotation based system (it derives the information from the ABS sensors so no extra hardware required). Some people experienced false alarms with it but the only time mine went off was a genuine event. Thankfully it wasn't a puncture just the result of driving over a pothole as far as I ever found out. It's not even a very prominent warning. I only noticed it after a short while. The Jazz gave an audible warning and the light was a lot larger and brighter.

So all in all (and considering future hassle and expense) I'm not enamoured of the Toyota TPMS. If it did what that after market system did and told us pressure it would be a lot better.

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I've just sorted mine out. The fronts had dropped from 33 to 30 and the rears from 30 to 29.

I've reset the TPWS. Took a while to work out how but for those unsure:

Use the left arrow controls and press left or right until 'Vehicle Settings' appears. Then press Ok. Then use up down to select TPWS then press Ok.

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12 hours ago, Cbatoday said:

Good to know. Do you have a link to the system you purchased

Sure - mine came from https://www.tyrepal.co.uk/product/solar-colour/

Some people I chat to on another group have recently bought what looks like the same system much more cheaply from Amazon or eBay - here's an example:

https://www.amazon.co.uk/dp/B07F74KV86/ref=dp_cerb_2

The users who bought this (after seeing my link to Tyrepal) reported that so far it's worked really well.  The supplier they used no longer has any left, and the price has risen slightly.

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Cheers have ordered the Amazon one.

Rather have something that monitors each wheel

 

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7 minutes ago, Cbatoday said:

...Rather have something that monitors each wheel

Same here.  I first bought mine before I had a car with a built-in monitoring system, but since it gives better information I transferred it to my last car and current one.

For the last couple of days I was lent a Lexus UX Hybrid while my car went on for a recall, and that could display individual tyre pressures on the dash.

It was the F-Sport model (no faster, but harder seats and suspension), and it also had a rather odd feature - a button that made it make pretend engine noises through the HiFI system including what sounds like gear changes (even when running in EV made!).

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One thing to remember with this type of valve cap sensor, is to make sure you put a good amount of anti-seize compound to the valve stem before fitting.  That will help stop the lock-nut and cap itself from corroding irreparably onto the valve stem on our salty winter roads.

  • Thanks 1

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On 12/4/2019 at 11:27 AM, rafletcher said:

One thing to remember with this type of valve cap sensor, is to make sure you put a good amount of anti-seize compound to the valve stem before fitting.  That will help stop the lock-nut and cap itself from corroding irreparably onto the valve stem on our salty winter roads.

Good tip thanks

Going to fit the kit this weekend. My wheels are 16inch and have the fronts set at 36 psi and the rears ar 35 psi

I have to set the kit with a lower and upper limit for the alarm to go off. Would you set the lower pressure to 29 psi and the higher pressure to 41psi on all tyres to give around a 20% variance

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I’d probably go + / - 5psi  max on those. 

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