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Discussion Starter #1
Pumped my tyres back up to 39psi yesterday as they'd dropped a few pounds since the temperatures dipped a few weeks ago. It occurred to me to ask the forum, given the performance charactistics of the Michelin 'green' tyres on the Ampera, if any of the experienced Ampera owners here did anything different with tyre pressures last winter when the snow and ice were about?
 
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Funnily enough I pumped mine up to 39PSI about 10 days ago and what a difference it made to both the colder weather range (up 4 miles at least) and the increased ability to "roll along"

Initially I'd pumped them up as I was doing a trip fully loaded. (I have to confess this is only the second time I've properly checked the pressures in 20 months)

I have detected a little loss of cornering grip (around all the Milton Keynes roundabouts) but that might just be what "summer" tyres would do in cold weather anyway. I seem to recall I had them at the upper level of pressure last winter without any problems so I'll leave them up there this time as well

Big Paul
 

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I have been running with winter tyres since buying my Ampera at end of November. I am just considering when to switch back, probably a couple of weeks or so from now (late March). The pressure information shown on the dashboard was showing 35, so when the car went back to the garage the first two times for a charging flap problem to be investigated, I asked them to check the tyres. Came back exactly the same. So the last time it went back for the charging flap, I was more explicit - make them 39 I said. They checked them again, and put another couple of psi in, but having had their own gauges checked recently, they reckon the in-car pressure gauges are a couple of psi out. So, I'm running at 39psi, but with 36/37 showing on the dash. Even after switching back, I intend to keep them at 39psi. The ride isn't that much different (noticeable, but not badly so) and I want to get as much range on battery as I can (whilst still driving with the flow of traffic). I do notice that the back has a bit of an issue, but not during normal cornering. It feels like if the nearside rear wheel loses traction (the potholes around here are a nightmare), rather than reduce power, there is a momentary kick in the back when the nearside rear gets grip again. It's disconcerting to say the least (not what I would expect from traction control) and I wonder what the result would be on ice, but I don't think it's related to the tyres or pressures. It will be interesting to see whether I notice the difference when I take the winter tyres off. I'll let you know.
 

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Discussion Starter #5
The pressure monitors on the wheels are not very accurate, mine are much like yours. Their main purpose is to flag up when there's a big difference in one tyre which means you may have a puncture - they've been useful in this way twice for me in the last 12 months (once a nail and once a piece of flint). I always use a simple 'slider' type gauge to check whenever I put air in.
 

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I would never rely on the tyre pressure sensors alone. As has already been said they are quite in accurate. I always use a proper tyre pressure gauge
 

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I have been running with winter tyres since buying my Ampera at end of November. I am just considering when to switch back, probably a couple of weeks or so from now (late March). The pressure information shown on the dashboard was showing 35, so when the car went back to the garage the first two times for a charging flap problem to be investigated, I asked them to check the tyres. Came back exactly the same. So the last time it went back for the charging flap, I was more explicit - make them 39 I said. They checked them again, and put another couple of psi in, but having had their own gauges checked recently, they reckon the in-car pressure gauges are a couple of psi out. So, I'm running at 39psi, but with 36/37 showing on the dash. Even after switching back, I intend to keep them at 39psi. The ride isn't that much different (noticeable, but not badly so) and I want to get as much range on battery as I can (whilst still driving with the flow of traffic). I do notice that the back has a bit of an issue, but not during normal cornering. It feels like if the nearside rear wheel loses traction (the potholes around here are a nightmare), rather than reduce power, there is a momentary kick in the back when the nearside rear gets grip again. It's disconcerting to say the least (not what I would expect from traction control) and I wonder what the result would be on ice, but I don't think it's related to the tyres or pressures. It will be interesting to see whether I notice the difference when I take the winter tyres off. I'll let you know.
John,

Re the tyre pressure accuracy I've noticed that the pressures on my car's monitoring display start at 38 but after any substantial journey have read up to 41psi even in this cold weather so I guess they might not match an external gauge but it's reassuring to know they do indicate even the smallest change in pressure.

Re the momentary "kick in the back" Im guessing you might just have the ESC (Electronic Stability Control) activating rather than Traction Controll. In the Owners Manual it suggests this can be deactivated but I'd not recommend it unless you are going for a qualifying lap at the Nurburgring!!!!

Big Paul
 
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