Tyre Pressures

[Guest]

To give an example of the opposite re narrow(er)tyres.

The recommended pressure for the 145/80 R14 76T Bridgestones fitted on my Morris Minor is 26p.s.i., front and rear. It's still a teeth jarring ride at that!

According to the driver's handbook, the recommended pressure for the old originally fitted crossplies is 22p.s.i..

With reference to Cyker's post and snow/wet performance, yes the narrower tyre tends to "cut" through the snow rather than try to ride over it.

I suppose a novel idea could be to just follow the car manufacturers' pressure recommendations? I suspect it's in the handbook if not on a pillar sticker or inside the glovebox lid.

[MikeSh]

40 minutes ago, mrpj1 said:

I suspect it's in the handbook if not on a pillar sticker or inside the glovebox lid.

These days they seem to like putting the plate on the passenger side pillar, which is annoying. Also there's the load options and different units too, which I rarely need, and it's often quite small print.

So, even if the maker's plate is there, I use a marker pen to write my normal pressures in my preferred units inside the driver door reveal in easily readable print. Saves a bit of squinting and trying to work out which number is 'the one', so less chance of error.

[alan333]

On 6/24/2022 at 12:44 PM, TonyHSD said:

 Also the reason, why we see lorries with disintegrated tyres on the motorway, simply because they had been overloaded and speeding. 

Not so sure about the speeding part.  Even when trucks are 'running on' down hills exceeding their max 56mph limiters, their tyres are made to withstand higher speeds.  I’m sure lots of us remember before speed limiters they all used to run along the flat at about 65mph.  

[MikeSh]

1 hour ago, alan333 said:

Not so sure about the speeding part.

I had an artic I was following blow a tyre. We were trundling along a Welsh A road at about 30-40 mph, so no speed to speak of.

I'd actually just floored the throttle to start overtaking him when there was this almighty bang. I thought my car had something seriously wrong, so I pulled back to check instruments and stuff, but it was all fine. Eventually, on left hand corners, I could see sparks from one of his left rear tyres, so I passed him and flagged him into a layby to tell him. There was about a 6" square flap of tread detached on three sides, hinging on the leading edge, with all the steel reinforcing sticking out - hence the sparks.

I don't think he was heavily loaded either, as after thinking for a minute he just carried on - presumably to a tyre shop.

100 psi is scary.

[Cyker]

Well done for letting them know!

For some reason truck tyres seem very prone to delamination; I suspect the extreme cost of them (A full set costs more than any one of my previous cars!) means re-treading them is more common than it is with car tyres.

They're also very vulnerable to low pressures - The high sidewall means they will overheat and fail much faster if the pressures are too low. Are TPMS a thing on trucks? Maybe on the cab but I guess it wouldn't be possible on the trailer...

 

[Rhymes with Paris]

I know that I am an old duffer rambling down memory lane.

I remember in around 1972 at the dogsthorpe housing estate in Peterborough when I was a young bricklayer, seeing a heavy grading machine.

I was in a commer crew bus waiting for the machine on a road crossing as we were leaving work, heading back to the digs at deeping st James.

The machine hit the kerb at speed and burst a tyre, maybe 8ft diameter.

The poor guy on the stop/go board nearby was thrown into the air a good way, and landed on the ground a way off 

He was covered in what looked like black bruising all over his body,it turned out that it was black coloured water that the tyre was partially filled with, I assume to keep temperature down.

No idea what the pressure was, but the volume of air and water alone was enough to throw a man a good way off.

Luckily, I heard the next day that he was ok but expected to be in hospital a while.

So yes, compressed air is pretty dangerous.

🤕

 

[Cyker]

Yikes, lucky that guy wasn't more seriously injured!  

But don't mind us; I for one love hearing such stories  

That reminds me of when I was trialling that Puncturesafe stuff in my tyres; One of the supposed benefits was that it would help keep the tyre from overheating as it was a semi-liquid gel moving around in the tyre. (But that's also why I stopped using it, as obviously liquid in the tyre plays merry hell with the balance, esp. at motorway speeds! It's a shame, as it worked surprisingly well; I saved me from having to repair several punctures while I was using it, aside from a sidewall tear which needed a whole new tyre...)

 

[Rhymes with Paris]

Ah yes,in my biking days there were stands at the bike rallies flogging ultraseal which was marketed as a pre emptive puncture repair.

Apparently it stayed liquid and coated the inside of the tyre with sealant, the blurb claimed that it was used in emergency service vehicles, never had it done so don't know how good or useless it was.

But a puncture in a bike tyre (motor bike that is) is a right pita,no spare wheel  ,and hours to wait for breakdown even if you had that.

Got back from Matlock bath with a nail in a front tyre checking every 5 miles or so , kicking it of course 😁

Do you reckon that the puncture safe stuff was the same thing under a different brand name?

[MikeSh]

30 minutes ago, Rhymes with Paris said:

Do you reckon that the puncture safe stuff was the same thing under a different brand name?

There are many different brands of 'goop' for bicycle tyres (useful in tubeless MTB tyres) and from the side-by-side testing reports I've seen they are definitely not all the same.

So no reason to think car and motorbike targeted products are all the same thing.

[Cyker]

I think the ultraseal and puncturesafe stuff is the same, but there are a lot of others as you say. The puncturesafe stuff is a bit unusual as it isn't just liquid latex with some chopped up rubber in it like a lot of them are  

It's also water soluble, which was a godsend when I needed to clean it out, as the garage wouldn't touch it with the stuff in it (I gather they'd had a lot of bad experiences with the aforementioned latex-based stuff)

 

[Roy124]

15 hours ago, MikeSh said:

I had an artic I was following blow a tyre. We were trundling along a Welsh A road at about 30-40 mph, so no speed to speak of.

The damage might have occurred earlier and only manifested itself later.  As for driving on, if lightly loaded possibly the best course of action rather than blocking the road for a few hours. 

[Roy124]

Back on thread, as I mentioned earlier, I found one cold tyre about 6 psi down.  I didn't have time to check the other 3.  After a few miles I had the opportunity to check the others.  They were all within one psi of spec. 

Next morning I rechecked and added 2-3 in each. 

In other words, an airline at the filling station is fine for inflating an obviously flat tyre, but if you want an accurate pressure do it when cold. 

I think a recent improvement in mpg might be harder tyres as well as warmer weather. 

[alan333]

13 hours ago, Cyker said:

Are TPMS a thing on trucks? Maybe on the cab but I guess it wouldn't be possible on the trailer...

 

No TPMS on any of the fairly new trucks/trailers at my work.

[TonyHSD]

6 hours ago, Roy124 said:

Back on thread, as I mentioned earlier, I found one cold tyre about 6 psi down.  I didn't have time to check the other 3.  After a few miles I had the opportunity to check the others.  They were all within one psi of spec. 

Next morning I rechecked and added 2-3 in each. 

In other words, an airline at the filling station is fine for inflating an obviously flat tyre, but if you want an accurate pressure do it when cold. 

I think a recent improvement in mpg might be harder tyres as well as warmer weather. 

True 👍

This is what I experienced all the time but at higher temperature margins.
My car stay parked all day under the sun then I drive through the night when no sun and air temperature drops by half . Btw when tyres are heated by the hot sun and even well over inflated the car drives much more comfortable that in the night when tyres gets back to lower psi, and it’s because  the rubber becomes very soft from the heat. 

[TonyHSD]

Don’t know why but last night decided to take pictures from the front tyres and they look very good condition to me. They are wearing equally and not showing any defects of yet. Hopefully will last me more. The winter set did not survived long, only 3-4 seasons. This Goodyear’s are on their 3rd season  and covered over 60k miles. 🛞👌

[RickyC]

On 6/24/2022 at 9:52 PM, TonyHSD said:

My story with the tyres and my current car. I switched from 215/45 17 down to 205/55 16 . The manufacturer recommended pressures at oem size 17”  were 2.3 and 2.2 bar. Since I swapped the tyres the new size obviously are softer with higher side walls I inflated them to the same values 2.3-2.2 front and rear and the car felt right but very soft , then I inflated to 2.4-2.3 bar and I had a bit of harder drive. Then I thought what was the point of having different size wheels and tyres if I have the same or worse comfort., I set the tyres at 2.35-2.25 bar front and rear on cold and since then I found my sweet spot, the perfect balance between comfort, rolling resistance, road noise and tyre wear. I do regularly check how they are wearing and tbh they do very equally front and rear on all 4 corners. 👌

Currently I've set my 205/55R16 to 2.4 Bar Front and 2.3 Rear.   I found them well balanced but a bit noisy.   I'll try to reduce the pressure to your values.  

When I first got the car from the dealaer they wher 2.6 on all wheels.  Car was a bit unstable. I set to 2.3 and was fine but noisy.  But I laeft them to this value.  When I got the car back from dealer after yearly check, the dealer told me he had set to the correct values ( 3 wheels set to 2.7 a rear one left to 2.3 ).  I found the car more silent and stable so i left all wheels to 2.6 for winter time ( I'm not using winter tyres ).  But when external temperature beagan to rise I reduced the pressure to avoid reaching too hig pressures ( I've seen pressure rising to 2.9 on front wheels ).  

By the way I've read of many users that got wheels overinflated by official dealers ( different dealers so I'ts no a specific dealer custom ).     

[TonyHSD]

16 minutes ago, RickyC said:

Currently I've set my 205/55R16 to 2.4 Bar Front and 2.3 Rear.   I found them well balanced but a bit noisy.   I'll try to reduce the pressure to your values.  

When I first got the car from the dealaer they wher 2.6 on all wheels.  Car was a bit unstable. I set to 2.3 and was fine but noisy.  But I laeft them to this value.  When I got the car back from dealer after yearly check, the dealer told me he had set to the correct values ( 3 wheels set to 2.7 a rear one left to 2.3 ).  I found the car more silent and stable so i left all wheels to 2.6 for winter time ( I'm not using winter tyres ).  But when external temperature beagan to rise I reduced the pressure to avoid reaching too hig pressures ( I've seen pressure rising to 2.9 on front wheels ).  

By the way I've read of many users that got wheels overinflated by official dealers ( different dealers so I'ts no a specific dealer custom ).     

Hi, 

dealers always over inflate tyres or simply does not check and adjust prior to delivery. Also many car garages has incorrect gauges or mechanics does not bother to carefully set the pressures, where I know that from mechanics themselves 😂👌. Best to check and set tyre pressure is at home in the morning before the sun has seen the car. Set them at the manufacturer recommended +/- 0.05bar . In winter best not to exceed the max pressure because the rubber is harder and you will loose comfort and grip. In summer you can go a bit above and even with pressure rises well above as a result of the sunlight the tyres will remain very soft, grippy and comfortable. As long as you not exceeding by much the recommended pressures you can’t go wrong. Every car will be different and every tyre make will feel different on the car. 
Regards 👍