The physics makes sense but does it translate into reality? Higher pressures should equal a smaller contact patch and less rolling resistance.

I know you loose a little grip, but for my usage that's not an issue - fuel consumption however is

Higher tyre pressures for reduced grip (so it takes longer to stop when that child runs out in front of you, and when you find that unexpected patch od spilt diesel), and for increased tyre wear.

The physics makes sense but does it translate into reality? Higher pressures should equal a smaller contact patch and less rolling resistance.

I know you loose a little grip, but for my usage that's not an issue - fuel consumption however is

I don't think the pressures are fully tested on cars, They seem a bit generic to me.

I prefer 36psi in mine. The ride is a little firmer but seems to handle better and get much better MPG.

I don't think 4 or 5 PSI is going to reduce grip tbh.

My Greenline II is supposed to have 38psi all round. But I find it a little hard so run with 36psi.

I don't think 4 or 5 PSI is going to reduce grip tbh.

You would be surprised! However you would only find out when you are on the tyres limit.

Hello 'Whitelighter'

Raised tyre pressures will decrease rolling resistance, wear on centre of tyres increased, compared to outer edge of tyre.

Increase braking distances especially in the wet, decrease grip on corners or turning left/right.

Quite frankly mate, you can't be serious!!!

Yet manufactures increas tp on 'green' models all the time. GL and BM cars ate typically 38-40psi compared to 33-35 psi for normal models

Yet manufactures increas tp on 'green' models all the time. GL and BM cars ate typically 38-40psi compared to 33-35 psi for normal models

Exactly so can't be that dangerous.

That was my point

Yet manufactures increas tp on 'green' models all the time. GL and BM cars ate typically 38-40psi compared to 33-35 psi for normal models

Best idea is to go by the manufacturers figures, use an accurate calibrate tyre pressure gauge and consider what the weight of the car is in total ie how much weight are you carrying ie passenger and junk in the boot and then interpolate your percentage added weight between the lower limit ie what Skoda say is say one or two passenger and a bit of luggage and full load ie full of passengers with heavy luggage therefore the max pressure advised.

People tend to under inflate as they are actually carrying more junk, by weight than they think. Doing Road Excises with DTP we use to do loads of cars, particualrly holiday traffic and beer runs as they were 10 to 40% loaded beyond their GVW easily done. Many cars, including Skodas, have a free weight of less than 500 kgs so get 4 or 5 adults and a bit of holiday purchases and they are well over weight.

Over or Under inflating will knacker either the centre or edges of the tyre so best get it right for cost saving you might save a few quid on fuel but have to change the tyres earlier as they have warn unevenly.

Keeping tyres at a constant monitored pressure, and look for signs for uneven wear.

This will give you a better insight whether to increase/ decrease pressures accordingly.

Keeping tyres at a constant monitored pressure, and look for signs for uneven wear.

This will give you a better insight whether to increase/ decrease pressures accordingly.

Exactly. I run my tyres 2PSI above what the label says all round, but that was based on several of us fitting the same make and size at about the same time, and all experiencing increased edge wear, so we could eliminate everything except the recommended pressure being too low for the tyres as a cause.

I tend to stick to manufacturers figures or one or two PSI over all round so if I carry passengers it covers it. Think the vRS estate is 36psi and I'll be checking them today.

The physics makes sense but does it translate into reality? Higher pressures should equal a smaller contact patch and less rolling resistance.

I know you loose a little grip, but for my usage that's not an issue - fuel consumption however is

Higher pressures are recommended for high speed use and when carrying a full load (to stop the tyres overheating) but only by around 3 or 4 PSI.

Don't forget, more than + or - 10% of manufacturers pressures and you could be in trouble with the law.

Tony

Don't forget, more than + or - 10% of manufacturers pressures and you could be in trouble with the law.

Tony

QFE

Car manufactures spend alot of time and money working out the optimal pressures for their cars. I've never understood the mentality of people who disagree with the people who designed and built their pride and joy.

Manufacturers set their tyre pressures for the optimum pressure considering ride comfort versus economy and even wear. Its always a compromise. Like my Greenline 1 the focus for Skoda was economy so they upped the pressures from a standard 32 ish to nearly 38psi. Its a cheap and easy way to up the economy. Its also sharper on the steering, grips fine but its a harder ride with more road noise. I can set these pressure legally because the sticker they bunged on the car tells me i can set these pressures. I also get perfect wear patterns to my tyres.

On my previous Fabia (non Greenline) I upped my pressures by 10%. Again better mpg, handling,grip & wear but I sacrificed ride comfort and tyre noise.

None of the above is rocket science, but as stated here there are laws about how you maintain your tyre pressures so its up to you how far you want to go.

I checked my pressures once after a long run on my Greenline. The pressures were almost exactly the max permitted for the tyre as specified on the tyre wall. Its easy to see where Skoda got their figures from.............

Keep the pressures within the manufacturers stated range (there is always a high and low figure) and you will be fine. Fir a fabia with 17" rims that is anywhere between 33psi and 44psi.

Don't forget tyre pressures also vary with atmospheric pressure and ambient tempteture plus with wheel tempteture

I've been running 40 psi in both fabia's, however yes definate better fuel economy roughly 5 mpg better than 36psi, the only problem the higher psi ruins ride comfort and noise, so taken down to 36 psi for the winter as all the tread will be in contact with the black stuff, also the cornering is less responsive with less psi I think, however the tyre's will wear normally rather than wearing in the centre

The other thing to remember is that tyre pressure will depend on temperature.

I see lots of people checking their pressures when the car is warm - even at motorway services.

I continue to be amazed that drivers are quite happy to run their cars with illegal tire pressures becoming a danger to themselves and other road users.

Tony

I continue to be amazed that drivers are quite happy to run their cars with illegal tire pressures becoming a danger to themselves and other road users.

Tony

Yawn

They aren't illegal tyre pressures.

I've put my psi up to 40 yesterday before driving to manchester today, and noticed a slight difference... when I had my 17's i used to have 45psi... and my economy increased dramatically...

I didn't think there was a law on pressures...?!

I've put my psi up to 40 yesterday before driving to manchester today, and noticed a slight difference... when I had my 17's i used to have 45psi... and my economy increased dramatically...

I didn't think there was a law on pressures...?!

Your right within reason. Click here its got a reasonable list of the relevant UK legislation.

As the law is ambiguous the 'safe' determination is the data on the tyre imho. The tyre states maixmum loading and tyre pressure. On my GL1 Skoda have clearly upped the pressure for economy based on the max pressure for that type of tyre. A standard car would have a pressure a few psi less for a more comfortable but less economic ride.

Provided you have an even wear pattern your at a safe pressure. If its overly worn in the middle then the sides arent contacting the road properly (over inflated) likewise worn on the outsides its under inflated (under pressure tyres bow inward in the middle reducing contact area)

The determination of whether a tyre is 'safe' in the eyes of the legislation is not solely determined by the manufacturer of the car. Its as much determined by the manufacturer of the tyre. The recommended tyre pressures are just that 'recommended' for optimum comfort and wear. You can bias this toward wear and economy to the detriment of comfort provided you dont go so far as to reduce or bias the tread contact area.

Its an arguement that gets banded around all the time.I dont give a monkeys what the car manufacturer says, if my tyres are wearing on the outside I will inflate them accordingly to even out the wear and make the tyres fully contact the road.....safer.

Edited 16 October, 201114 yr by raisbeck