It Happened Again

[vw bobby 10]

Hi All

 

Driving home from work and basically it was running low on air, went to the petrol station to put air in, but the valves are too small. Tried nursing it home and 50 yards from the petrol station this happened:

 

 

[kerrly 0]

Stretch tyres???? Or it could be the sidewall is damaged as a result of driving whilst flat?

[VR6 0]

Another dodgy tyre??

[vw bobby 10]

Hopefully this time round it was just low pressure

[VW_OwneR_85 2]

air pressure is what holds the tyre in place, if you had a wider tyre then it probably wouldn't of popped off the bead the way it has there, unless im missing something here like the side wall has blown out? ,

[vw bobby 10]

No that is exactly what happened, low air

[MarkFoster 0]

Maybe it's the tyre god's way of trying to tell you something.....?

[clumpy1 11]

Maybe it's the tyre god's way of trying to tell you something.....?

:lol: you could be right there Mark. Bobby is that the corvette's?? Again?? Too much stretch?? :bonk::bonk:

[vw bobby 10]

Yes mate its on the vette wheels again. But when I use my BBS on my yellow rado, I will not be running stretch this time round.

 

I have learnt my lesson :bonk:

[GrahamU 6]

I have learnt my lesson :bonk:

 

 

you know it makes sense

[vw bobby 10]

very true mate

[bristolbaron 10]

hmm.. is it too early to say i told you so? theres really no issue running a decent stretch providing you stay around 38-40psi. AND CHECK REGULARLY! You are the reason people say stretched tyres are dangerous! :lol:

[vw bobby 10]

hmm.. is it too early to say i told you so? theres really no issue running a decent stretch providing you stay around 38-40psi. AND CHECK REGULARLY! You are the reason people say stretched tyres are dangerous! :lol:

 

Yes I agree if I want to run stretch tyres, I will be putting 38-40psi in and checking regularly

[Critical_Mass 10]

Another dodgy tyre??

 

:lol:

[kerrly 0]

hmm.. is it too early to say i told you so? theres really no issue running a decent stretch providing you stay around 38-40psi. AND CHECK REGULARLY! You are the reason people say stretched tyres are dangerous! :lol:

 

 

And where exactly is the science that says 38-40PSI is what is needed? I'm not having a go at you as I can tell from your first comment that your reply is a bit tongue in cheek, I just find it bonkers that this trial an error approach results in giving general guestimates about what magic number will allow incorrectly fitted tyres/wheels to "work"

 

Each to their own I guess.

[seanl82 23]

And where exactly is the science that says 38-40PSI is what is needed? I'm not having a go at you as I can tell from your first comment that your reply is a bit tongue in cheek, I just find it bonkers that this trial an error approach results in giving general guestimates about what magic number will allow incorrectly fitted tyres/wheels to "work"

 

Each to their own I guess.

 

Has nothing to do with the stretch, but profile and size of tyres should be (generally) 2 psi with each step, above standard fitment iirc.

[kerrly 0]

^ interesting, first time I have heard that one. So for instance a standard 205/50/15 on a Corrado is 32psi and you fit 205/45/17 instead.

 

So the new wheel is 2 inches bigger in diameter but the overall diameter of the wheel & tyre is barely over an 1inch difference. Thus if it's 32psi standard, using your principle am I right saying 34psi for 16 and 36psi for 17 but that only works IF the tyre ratio is maintained as per factory IE 205/50 so reducing the tyre profile thus reducing the side wall area throw that calculation out?

[GrahamU 6]

All that use this pressure use that pressure is all a bit pie in the sky, I can guarantee none of you check your tyres regularly enough to know what your running from one day to another.

 

Most of you wont even be checking your tyres at the right time when you do check them.

[Dox 23]

All that use this pressure use that pressure is all a bit pie in the sky, I can guarantee none of you check your tyres regularly enough to know what your running from one day to another.

 

Most of you wont even be checking your tyres at the right time when you do check them.

 

Well don't keep all your knowledge to yourself :)

[kerrly 0]

^ quite.

I don't like the use of stretch tyres but I am very interested in more information about tyre pressures

[Philuk 0]

i never had bother with the stretch tyres on the schmidts and never had any bother with the stretch tyres on the gfs golf. how much stretch were you running!?

[Dox 23]

http://the-corrado.net/showthread.php?t=83559

[davidwort 0]

Funny, I thought stretched tyres was obviously a dangerous thing, it just looks mechanically wrong, but the internet seems to think otherwise.

I bet an insurance assessor would have something to say though if you're involved in a serious accident and the tyres were clearly intended for rims half the width.

 

Edit:

I'm more likely to trust advice from someone like Yokohama:

http://www.yokohamatire.com/tires_101/customizing/rim_wheel_width/

 

Each Yokohama tire has a specific rim width range on which the tire can be mounted. Failure to follow rim width recommendations may result in poor tire performance or possible wheel and/or tire failure.

 

 

Cheers for the advise guys, and yes these are streched on 9.5 x 16's with 205/40/16

 

according to yokohama you should have tyres about 4cm wider on those

Edited December 4, 2013 by davidwort

[GrahamU 6]

All that 'use this pressure, use that pressure' is all a bit pie in the sky, I can guarantee none of you check your tyres regularly enough to know what your running from one day to another.

 

Most of you wont even be checking your tyres at the right time when you do check them.

 

^ quite.

I don't like the use of stretch tyres but I am very interested in more information about tyre pressures

 

 

I cant comment on the use of stretched tyre pressures as I don't like them but here are my reasons for my statement above.

 

Most of it is common knowledge and manufacturers recommendations.

 

The first thing to remember is that although you check the pressure when cold, the tyres will heat up as you drive and the air will expand, this will be at different rates and to different pressures. It is this pressure you will be running on, not the pressure you set them to when cold.

 

There are many variants to take into account when it comes to tyre pressure, these include weight, temperature, atmospheric pressure, how good is the equipment your using to inflate/check them, have you driven to a garage to check them, etc.

 

Manufacturers say to check the tyres once a week but most drivers dont do that.

 

Even if you checked every week, the change in atmospheric temperature can be sufficient to alter the tyre pressure by a couple of psi. If you checked first thing in the morning on a summers day, the temperature by the time it gets to lunchtime will change your tyre pressure, even the type of road will make a difference, a black tarmac road will absorb the heat on a sunny day and transfer to the tyre carcass more than a grey road surface.

 

When you check the tyres, how good is the pressure gauge, has it been damaged by the general public abuse, when was it last calibrated and how far out is it, what is the tolerance of the gauge. Again, these can all alter your pressure by a couple of psi.

 

Then the main one is have you driven to the garage to check them. If you are trying to get a recommended pressure then that is a big no no.

 

The graph below shows the rise in temperature as the car is driven, the pink/red line being the temperature of the air inside the tyre and the yellow being the temperature of the tyre carcass.

 

 

Then this graph shows the rise in tyre pressure for the same drive (please note the pressure shown is in absolute which reads approximately 1 bar higher than gauge pressure).

 

 

You can see, it doesn't take long for the temp and pressure to rise enough to make your check after the drive to the garage inaccurate.

 

Check your tyres when they are cold and haven't been driven on using a known good accurate pressure gauge, preferably your own.

 

If the weather changes the next day to be several degrees hotter or colder, your setting from the day before will be wrong.

 

Then theres the tyre itself, if it has a soft compound, the rubber will move around a lot more causing the tyre to get hotter when your driving and therefore changing the pressure of the tyre when it reaches its running temperature.

 

Little things can also change tyre temps, I have seen when testing the tyres on a car that the airflow across the tyre can alter the temp and therefore the running pressure, damaged or modified arch liners can make a difference. On your Corrado, do you still have the brake ducts as that will change the amount of airflow over your tyre.

 

Do you drive on motorways or round twisty roads as that will also affect how the tyre works. Do you take short journeys or long

 

How is your suspension set up, camber, tracking, have you got coilovers, has the weight been setup for each corner.

 

What gas are you using in your tyres, if your using normal air then what was the humidity of the air when you filled them, higher humidity air will expand at a slightly different rate to low humidity.

 

Like I say, lots of variants to take into account that all can make some difference to the running temperature/pressure of your tyres. There are many more things than all this to take into account aswell.

 

 

 

 

 

In my opinion, and it is only a recommendation, the best place to start for your tyre pressure is the manufacturers recommendation for that car, that will be a compromise for many different scenario's, from there keep an eye on the tyres and check for any uneven wear and adjust each tyre to suit.

 

For a person on any forum to say, you need to set your tyres at this pressure is still only a guesstimate and should not be taken as gospel.

 

I run TPMS on my car, the same one that winning team use on their F1 cars so I see how much variation I get in my tyre pressures for different journeys on different days.

 

Hope that makes some sense, but I know there are some that will argue my points :)

Edited December 4, 2013 by rado20vT

[Dox 23]

Give us some stats from your TPMS, how much variation in pressure from say your journey to work or a longer motorway trip? :)