Winter tyre pressure management and effect on range

[AussiePete]

As the outside temperature begins to drop (it’s 8 degrees here in Scotland today) I’ve noticed a step change in the range (actual not GOM). I usually get over 4 m/kw in the warmer weather (approx 160 mile range) but yesterday in the rain and low ambient temperature and wet conditions I noticed it dropped to less than 3 m/kw (approx 120 mile range) - in part this is as I also had the heater on . I know this is to be expected as cold temp = reduced range.

However one thing I have noticed is that in the warm weather the tyre pressure at driving temperature is 2.4 bar however in the cold weather it’s 2.2 bar. I expect this will contribute to the range degradation so plan to increase winter pressure to at least 2.4 bar.

Would be interested to know if anyone else has seen this and if the range degradation is reduced by better winter tyre pressure management.

 

[Alb]

Have you reset you cold pressures to the correct figure?

 

[AussiePete]

Have you reset you cold pressures to the correct figure?

@Alb what do you mean? Tyre pressures change with ambient temperature, so when sitting on my drive in summer (when ambient temperature was around 18-20 degrees C), the tyre pressure will be higher than they are now when the ambient temperature is much colder (around 8 degrees C). As such in winter you need to adjust the tyre pressure to ensure its at the recommended pressure.

 

[Webbo]

@Alb what do you mean? Tyre pressures change with ambient temperature, so when sitting on my drive in summer (when ambient temperature was around 18-20 degrees C), the tyre pressure will be higher than they are now when the ambient temperature is much colder (around 8 degrees C). As such in winter you need to adjust the tyre pressure to ensure its at the recommended pressure.

If your range anxiety is so great that you worry about tyre pressure, I think you bought the wrong car!

 

[macd2401]

@Alb what do you mean? Tyre pressures change with ambient temperature, so when sitting on my drive in summer (when ambient temperature was around 18-20 degrees C), the tyre pressure will be higher than they are now when the ambient temperature is much colder (around 8 degrees C). As such in winter you need to adjust the tyre pressure to ensure its at the recommended pressure.

I think what they were asking was have you got your tyres to the recommended pressure now. Cold pressure is just the pressure when the car hasn't been driven for a few hours.

Most drivers are terrible for not checking their tyre pressures. It should be a weekly check, some folks never do it...

 

[AussiePete]

If your range anxiety is so great that you worry about tyre pressure, I think you bought the wrong car!

@Webbo it's not range anxiety, it's an observation about the vehicle when the temperature drops

 

[AussiePete]

I think what they were asking was have you got your tyres to the recommended pressure now. Cold pressure is just the pressure when the car hasn't been driven for a few hours.

Most drivers are terrible for not checking their tyre pressures. It should be a weekly check, some folks never do it...

I check every other week as well as keeping any eye on the running pressure through TPMS

 

[AnonymouseDriva]

If your range anxiety is so great that you worry about tyre pressure, I think you bought the wrong car!

In all honesty, if I would have had TPMS and a trip MPG readout in my Scenic I would have been asking exactly the same question as @AussiePete.
I had also noticed that the cold (i.e. not running) tyre pressure had dropped along with the recent ambient temperature drop.

 

[Trevor Wootton]

Is it not better to have a slightly reduced pressures in colder conditions to give a larger footprint hence more grip in the snow and ice? I usually run a few PSI above the recommended pressures in summer but I'm more concerned about keeping all 4 at the same pressure so my car runs in a straight line.

 

[Cocijo]

Your tyres get warm on a journey - particularly at higher speed. The biggest impact on range is always going to be temperature and driving style.

 

[AnonymouseDriva]

Your tyres get warm on a journey - particularly at higher speed. The biggest impact on range is always going to be temperature and driving style.

Yeah,, that's why I haven't done anything yet. I noticed that the miles/KwH from cold has dropped, but soon picks back up. the real question is how much the air temp affects the running temp of the tyres. If they still warm up to roughly the same temp through usage, then it doesn't matter, but if they generally go to x degrees above ambient, then they probably need a touch more air as winter sets in. They're already showing 2.1 bar cold instead of the recommended 2.2 (i'm in a 5), so that will drop further as it gets colder.

 

[Alb]

@Alb what do you mean? Tyre pressures change with ambient temperature, so when sitting on my drive in summer (when ambient temperature was around 18-20 degrees C), the tyre pressure will be higher than they are now when the ambient temperature is much colder (around 8 degrees C). As such in winter you need to adjust the tyre pressure to ensure its at the recommended pressure.

The recommended "cold" pressure is a fixed starting point so tyre pressure should be adjusted (cold) whenever ambient temperature moves it away from the design figure. You don't necessarily have to do this day by day but once a week would be sensible.
ΔT when running should be broadly similar for Winter or Summer.

 

[Deleted member 2439]

@Webbo it's not range anxiety, it's an observation about the vehicle when the temperature drops

EV range is adversely impacted by lower temperature……..

 

[Kithmo]

Having slightly lower pressures in cold weather will improve grip as the tyre flexes better. This is the same principle as Winter tyres, they have softer compounds than summer tyres.
I just set my tyres at the recommended pressure in Winter and then they naturally go slightly higher in Summer on their own.

 

[Paulie68]

Wheras tyre pressure will affect range a little, the big reason for noticing a large drop in range is the combination of colder weather and wet conditions. Especially the wet roads, which cause a huge increase in rolling resistance. I agree fully with the earlier poster in not increasing pressures in wet conditions, as it will lower grip.

 

[Exdro]

Would not recommend higher TP in winter as it will reduce the footprint and hence the grip. I have calibrated mine in PSI as it is easier to adjust small increments on a larger scale.
If you turn on the TP monitor you can see how the pressure changes as the tyre warms up. If you hit a couple of rough edges/small potholes on one side you will see how compression of the air inside the tyre warms up and increases the pressure. Basic physics from my O level days. as gas is compressed, the temperature rises. Boyle's and Charles Laws on compression and expansion of gases. As long as all tyres are the same pressure or at least those on the front and back axles are the same then traction should be ok.