Hi guys,

 

I've been looking everywhere for this information as I think the inside of the fuel hatch is wrong.

 

I have just fitted my Octy 2.0 TDI stationcar/estate with the new Golus 18" rims with the Continental SportContact 2 tyres (235/50 R 18). The tire wall only states what maximum pressure should not exceed and weight constrains per wheel. The inside of the fuel hatch says 2,2 - 2,4 bar for 2.0 TDI with 235/55 tyres,  depending on passenger load.

 

When mounting the wheels they were inflated to 2,8 bar (even after spending 5 months in the garage) and deflating them to 2,4 caused them to look like I've run flat. I mean, they were really bulging out. Even at 2,8 the front tyres looked at little squeezed. At 3,0 they looked like they should so I've kept them there but I don't like driving around on "intentional look", I would rather have the correct tyre pressure.

235/50 18 isn't the right size though is it? That's a really high profile tyre and it going to look odd.... Should they not be 225/40?

235/50 18 isn't the right size though is it? That's a really high profile tyre and it going to look odd.... Should they not be 225/40?

 

Agree on that. Mine are 225/40 on CS 2, otherwise they would look a bit weird. Why did you put that tire on out of interest?

I'm quite sure that it is some wrong tires you put on. 235/50/18 has a rolling radius of 2114mm. 225/40/18 are rolling radius of 1943mm. require changing the rolling radius by 5% and in your case you are up to 10%

235/50/18 and 235/55/18 are waaay too big for the Octavia, like the others have said. The larger the tire you go, the higher pressures you need to keep it inflated (look at truck tire pressures). Obviously, if you put the pressure from 225/40/18 (which is what you need) in a 235/55/18 tire then it's going to look deflated.

 

I'm afraid you bought the wrong tires! Unless you're remembering the numbers wrong.

The larger the tire you go, the higher pressures you need to keep it inflated (look at truck tire pressures).

 

I've never heard this before.  Pressure is pressure and I thought was weight related.  We ran a Caterham with 185/55 13 tyres and ran those at about 18psi.  I always remember taking my mk4 Golf into VW for a service and they said they wouldn't checked the tyre pressures.  It had Audi TT rims with 225/45 17 tyres, much like the option Santa Monticas with 225/45 17.

 

I agree with the others that the 235/50 is the incorrect tyre for the rims

Well yes, but obviously you're putting larger tires when you have a larger vehicle -> the tire needs to support more weight.

 

Unless you like dubs, of course.

Edited 11 March, 201412 yr by TudorM

Yeah, stupid me. I was looking at Continetal's webpage... they are not featuring the right tyre names   So much for goldfish memory.

 

It is the factory mounted tyres on the Golus rims, it IS the 225/40 R18 92Y... despite the corrections here, I still cannot find the right tyre pressure.

Does it not state in the manual what the tyre pressure should be for that tyre size? There is usually a data table (at the back) with this sort of information.

Should be 225/40 R18 if you have 235/50 R18 you have Jeep tires on the car ... Must take in the displays when you turn and must look really strange. 

These tires can not have been from the factory, or have you seen right?

For me, always maximum pressure, as stated on tyre sidewalls.

 

The inside of the fuel hatch has only a generic information. Maximum pressure depends on tyre.

 

I was congratulated for the even consumption, even if I never prevented them from fast bends and fast (but not stupid burning) accellerations.

 

The ride will be more on the harsh side, but more precise. As a side effect fuel consuption will also benefit from less losses.

 

HTH.

I have mine set to 2.3 bar all round, which is just fine with no rear seat passengers or luggage. The rears should be increased to approx 3 bar if fully laden.

http://www.continentaltire.ca/www/download/tires_ca_en/themes/pcar/summer/hidden/datasheet-csc_2_en.pdf

 

51 PSI = about 3.5 bar (max pressure)

Edited 11 March, 201412 yr by Genoa1893

Trolling?

http://www.continentaltire.ca/www/download/tires_ca_en/themes/pcar/summer/hidden/datasheet-csc_2_en.pdf

 

51 PSI = about 3.5 bar (max pressure)

This only quote max design pressure of 51psi, that is not what you should inflate to, you should inflate to the values indicated on the vehicle inside the fuel filler flap.

Trolling?

 

Pardon?

This only quote max design pressure of 51psi, that is not what you should inflate to, you should inflate to the values indicated on the vehicle inside the fuel filler flap.

 

Your mileage may vary. I simply suggested the OP my practice, which is to inflate them to max pressure. Hope you can understand, and of course the OP shall evaluate the feedbacks.

 

Best,

For me, always maximum pressure, as stated on tyre sidewalls.

The inside of the fuel hatch has only a generic information. Maximum pressure depends on tyre.

I was congratulated for the even consumption, even if I never prevented them from fast bends and fast (but not stupid burning) accellerations.

The ride will be more on the harsh side, but more precise. As a side effect fuel consuption will also benefit from less losses.

HTH.

Sorry, you cannot seriously be offering this as advice on a public forum?

I hope I am nowhere near you when you have to do an emergency stop from 70mph, you will only have about half of your tread in contact with the road and will take a considerable distance to stop on your balloon, sorry tyre pressures.

Manufacturers of both the car and the tyres spend a fortune on R&D, and recommend a particular pressure for many reasons.

Yes, you can achieve better mpg on higher pressures, but at the expense of what? - safety and tyre wear?

I would strongly suggest 10% either side of the recommended pressure is the furthest you should go.

As for the OP saying that they look deflated, are they the correct load index I.e sidewall strength?

As a general rule, as you lower the profile you need to increase the load index. I think (haven't checked) that they should be 92 load index and a minimum of Y speed rating.

Sent from my phone so please excuse brevity and spelling

Pardon?

I was suggesting that you posted just to get a rise from people.

If you inflate your tyres to the maximum pressure on the side wall, what happens after a long journey and the tyres (and thus air inside) have warmed up? They will now be above the maximum stated pressure.

Edited 11 March, 201412 yr by SC03OTT

Sorry guys, I think I have explained my view, or better my experience after having driven for many years about 300km per day on fast highways, and having tried several different settings and tyres on my oldie VRS TDI 170 (@SC03OTT the tyres never ever had any issues even after 600Km journeys at sustained speeds, with bends). When I told the tyreman congratulated me, I must say he was a old professional, with many years of specific experience (@andyvee) the consumption was even, so the contact of the "baloons" was even on all the surface.

 

Of course you're entitled to have your opinions and tastes and, consequently, advise the OP.

 

As an engineer I am pretty sure the max pressure stated by the manufacturer already takes into account a good safety margin and I'm also pretty sure the values reported on the fuel hatch takes into account many factors such as "comfort" (between quotes, since I for sure prefer safety and precise steering to a soft and muddy response as that given by under inflated tyres).

 

I posted on the basis of experience and logic. But again YMMV. Don't think I need to further explain my point.

 

Best,

Edited 12 March, 201412 yr by Genoa1893

Stirring up the bri-hive 

 

Anyways, I'll get some photos of the tyres with the different inflation levels on my way home today. Max pressure on the sidewall does display 51 PSI (nothing in bar, compressors at gas stations in DK features only Bar scale).

 

3.0 bar might not be that far off ideal pressure if max is 3.5. I am certainly not inflating them to max. Maybe Italian engineers know better, my knowledge tells me that the tyre pressure should correspond to the tyre load. Unless you're driving around with ~630 kg pressure on each tyre you should not inflate to 3.5 bar.

the pressure stated on the tire sidewall is the maximum pressure. If you get too much pressure in the tire will be worn in the middle. Is it foreksembel a goodyear steel tracked down the middle, they are worn on the shoulders. Will there be enough pressure in the tire will be worn on the shoulders. The pressure of the tire depends on the weight so the tongues car the greater pressure at the same tire size

For me, always maximum pressure, as stated on tyre sidewalls.

 

The inside of the fuel hatch has only a generic information. Maximum pressure depends on tyre.

 

I was congratulated for the even consumption, even if I never prevented them from fast bends and fast (but not stupid burning) accellerations.

 

The ride will be more on the harsh side, but more precise. As a side effect fuel consuption will also benefit from less losses.

 

HTH.

 

Best of luck 

Don't know if it'll help or not as I've got the vRS Estate but I run the 225/40/r18s on mine with 2.3 bar all round, although I've increased to 2.4bar for the winter tyres as get more grip - I'm keeping an eye of the thread to see if it's under or over but apparently winter tyres car be a bit softer an need more pressure.

 

Below is a pic of my flap

Don't know if it'll help or not as I've got the vRS Estate but I run the 225/40/r18s on mine with 2.3 bar all round, although I've increased to 2.4bar for the winter tyres as get more grip - I'm keeping an eye of the thread to see if it's under or over but apparently winter tyres car be a bit softer an need more pressure.

Below is a pic of my flap

IMG_1003.jpg

Spot on.

Sent from my phone so please excuse brevity and spelling