Following on from the "Mr Average or in minority?" thread.
With lower profile tyres now being the norm, how important is inflation pressure?
My offspring have absulutely no interest in their cars and I usually end up inflating their tyres when they visit, but I've noticed they still seem to wear evenly despite being down to around 60% of recommended pressure.
I've played around with my own tyre pressures a bit (195/60 x 16) and even running at 10PSI above recommended I've not noticed any difference in economy.
I'm reluctant to run them below the recommended pressure, but wonder if anyone's measured the difference in grip and economy at different pressures for modern lower profiles?
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generally, the lower the profile the more important the pressure !
Rule of thumb, not rule of physics!
If you cant tell the difference between pressures (10 psi or more) I am surprised to say the least!
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If mine drop below a certain level (maybe around 4 or 5 psi below recommended) I can feel it straight away when I'm driving. On any corner or bend I can feel the car wallowing and bouncing a bit more than it normally would and I certainly don't feel as safe or in control of it as I would be if the pressures were correct. It just feels tighter, direct and more in my control.
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If mine drop below a certain level I can feel it straight away when I'm driving.
And me, Sid... it can make quite a difference on those cars without power steering as well...
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Underinflated causes sidewalls to get hotter and so can cause a blowout sooner rather than later plus underinflated tyres are more likely to get a shoulder puncture.
I think what you are saying is that modern low profile tyres dont show as flat on a vehicle as say a 155x13 on a cortina would and so by nature and lazy people they look at their tyres sometimes even give them a kick but never actually check pressures,i did a bit of a customer question thingy earlier this year asking younger customers if they knew what the long slim tyre pressure guage in my hand was,i dont remember anybody actually guessing correctly
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I might as well add that something like 80% of cars i buy in have at least one wrongly inflated tyre and usually all of them are either on something like 12psi or 60 psi some people either just give them a damm good pumping or dont bother at all
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lower profite tyres have stiffer sidewalls so dont show low pressure. Its still very important though and you can feel low pressure by tyre squirming when you steer.
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Well - as I seem to be the person who sparked this thread - I can certainly tell the difference when an odd tyre pressure is out by even a few pounds.
Yesterday it was persisting down with rain but I still carried out my weekly check...
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Regarding over-inflation:
when my Passat was delivered in 1997, on the journey home along the M4 I was appalled by the road noise and wondered how I was going to live with it for the next 4 years. At home, a quick check revealed all 4 tyres grossly over-inflated (so much for the pdi!); setting them correctly transformed the car (now at 203k, btw) into a comfortable motorway cruiser.
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(so much for the pdi!);
I think every new car I've ever bought, apart from my Mercedes where they were spot-on, had had quite to very overinflated tyres.
Regarding fuel consumption - various tests have been done and it makes surprisingly little difference.
On thing I would say is that with the modern trend of very low profile tyres then reasonable pressure is vital to minimise pot-hole damage to the wheel.
Edited by Bill Payer on 29/12/2009 at 17:18
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Yes - Tyre pressures are critical to safety - anyone who has ridden a bike with less then nominal pressures in the back wheel will now what a difference it makes long before wear becomes an issue. I was laughed at for checking oil levels in the CRV this afternoon - sorry that's what motorcycling does to you.
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I am shocked at how badly the low profile tyres on the Subaru perform it seems one is always in need of topping up and it has got to the point now that if I clatter a pothole I can guarantee that the tyre will need several pounds straight away.
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I have had three Saab 95 Estates. The first one was on 16-inch rims, the second on 17-inch low profile (Vector Sport) and now I'm back to 16-inch. The low profile jobbies needed constant fiddling with particularly if they had a rough and bumpy week ... and also gave a teeth-rattling ride ...
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with a hard winter likely to rip up the roads, and cash strapped councils unable to fix them, I suspect low profile shod drivers are in for a very hard time.
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Some people suggest that by reducing tyre pressure it helps in the snow, is this true and how much does the pressure need to be reduced by to help?
Thanks
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>>Some people suggest that by reducing tyre pressure it helps in the snow
Seems to work - I came across some chaps letting their tyres down to get out of an iced over sloping car park they were stuck in last week - old Escort. It worked.
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Seems to work - I came across some chaps letting their tyres down to get out of an iced over sloping car park they were stuck in last week - old Escort. It worked.
But how much does the tyres need to be deflated by ?
Thanks
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>>But how much does the tyres need to be deflated by ?
I don't think they were that scientific - they let them down until they looked half flat, so you wouldn't have wanted to go very far at all, or at any speed - they just wanted to get out of the car park.
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>>With lower profile tyres now being the norm, how important is inflation pressure?
Very, as far as I'm concerned. I borrowed my wife's car a few months ago. Changed lanes more smartly than usual at about 70mph, and got a bit of a tank slapper on - not often seen with a 2002 Civic! Turned out the O/S rear tyre was at 10psi, although it "looked" normal.
She was duly summoned for a cup of tea with no biscuits. Still turned out it was my fault - not sure how that happened!
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The best tyres for snow duty are tall and thin, the very opposite shape of a tyre under inflated !
However, for ice, a wider tyre spreading the load would be more beneficial.
Now, do I want tyres for snow or for ice? or for normal roads? decisions decisions!
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The tyre needs a certain minimum pressure in it just to keep it on the wheel.
www.michelin.co.uk/michelinuk/en/car-van-4x4/what-...l
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Yes!
In trialling and grass autotesting I've found anything below 12PSI in, dry conditions, risks rolling the tyre off the rim.
I now intend fitting inner tubes to my off-road wheels.
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For the last two sets, I've run the Octavia at higher than the manufacturers figures, about 38psi, and have seen more even wear on the front and slightly better mileage, about 19000 off the front pair. I tend to run all the cars a few psi above now. I feel that it sharpens up the steering a little, but yes, the ride suffers a little too. When I had the Focus, which I detested for its road roar, amongst other things, I tried reducing the pressures slightly below but it had no noticeable effect.
I check them every week and a quick visual check every day, agree, it becomes habit if you ride a bike. I had a puncture on the Bandit last year and first noticed something wrong at speed on the dual carriageway. Half a mile later, the tyre had started to melt and was smoking visibly!
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