New Polo GTI tyre pressure - 360kPa seem high?

[Scott01]

Hi Guys,

Had my gti a couple months now and checked the tyres - pressure was 360kPa, tyre placard recommends 250 front / 270 rear. Seems like a big difference to me. What should I go with / why? I dropped them to 250/270 and can't really pick the difference. Should I up them back to 360? The first 3000kms on that seemed fine and must've been done by vw for a reason?

Any suggestions or help would be great.

Cheers
Scott

[Diesel_vert]

No!
You should NEVER exceed 3.5 bar (350 kPa or 51 psi) for any high-speed passenger tyre in general. Always check the tyre's sidewall if in doubt.

The tyres are inflated to maximum pressure (3.5 bar) at the factory, and are supposed to be re-inflated to the correct pressures during the delivery inspection - but someone obviously forgot.

Interesting that you say there's little difference - do you feel the ride is somewhat unusually harsh? Makes me wonder if they forgot to remove the blocking pieces from the front axle springs, or anything else for that matter...

Or it could just be a dodgy pressure gauge, lol.



In regards to inflation pressures, consider the pressures on the fuel flap as the minimum, and whatever pressure you are warned not to exceed marked on the tyre's sidewall as the maximum. Anything between these two limits is fine.

[gavs]

Most people have found that their tyres (that check them anyway) are WAAAAAAY over inflated at time of delivery and are clearly not being rectified at the QA at pre delivery stage.

Wonder how that would go with warranty if one exploded on someone

[Scott01]

Thanks guys.

Just checked the tyres and max rated pressure on these (Dunlop SP SportMaxx 214/40R17) is 340kPa - so yes, they were over-inflated.

So what should I put in my tyres? What would people recommend?

Taking the placard as minimum and tyres as the maximum, this gives me a range of 250/270 to 340kPa.

Even on the 360kPa originally in there the ride felt ok to me (I'm no expert at spotting these things), so should I go with max pressure -10%?

Does max -10% allows enough room for pressure build-up on longer drives, or if I drove a bit harder (Guess it depends on what "bit harder" means, but my bit harder is probably still very tame to most). Or would I need to reduce pressure if I wanted to do this?

Any situations where I should be putting something different in?

Thanks for the help guys - much appreciated!

Scott

[antihero3000]

Interesting, i've run all my cars at 30/32psi. Why would VW over inflate these so much from the factory?

[gavs]

Adds more height so it doesn't scrape going on and off boats and transports etc.

The recommended placarded load converted to psi is around the 39psi front and 36 rear, unless you're loaded up in the rear which changes to 39 front and 41 rear.

I just run 39 psi all around. 30-32 psi is too low for a low profile tyre.

[babs]

When i checked the pressures after driving from the dealer i found it was only around 32 psi so when i went through ditches and humps the car felt so bouncy that i felt like the car was on a jumping castle. After inflating it to 39 psi then it felt much better.

[noone]

Depends on the tyre. being front heavy and FWD, I'd put a few more PSI in the front than the rear.

Ballpark of 36 in the front and 34 in the back for normal conditions for me. if no swaybars, a few PSI higher at each end (38/35 maybe)

[Scott01]

Ok - so sounds like I can probably stick with 38/40psi or 40/42psi which works out to the "250/270 - 290/270 kPa" on the tyre placard.
Sounds normal and along the lines of what others are running with.

One question though - the tyres can take up to 340kPa (49PSI)... any reason why you would or should use this much pressure?

[Diesel_vert]

One question though - the tyres can take up to 340kPa (49PSI)... any reason why you would or should use this much pressure?

There are two situations that I can think of:

1. The vehicle and/or tyre manufacturer specifies it.

2. When a vehicle is in long term storage, with the wheels & tyres installed and supporting the vehicle.


Other than that, I see little benefit from driving on tyres inflated at maximum pressure unless specified.

[jrgti]

360Kpa???? wow. Even my golf gti Mk6 don't even specify that high on the petrol cap. 280Kpa front max/ 300Kpa rear max (17inch stock wheels and tyres - Potenza's)

[Scott01]

Jrgti - The petrol cap says 270/250kPa - 290/270. 360kPa was what I found in the tyres themselves after picking it up. Sounds like overinflated for transport/shipping and dealer forgot to check and set this.

Given others comments on here, 270/250 sounds like reasonable so I'll stick with this.

[GTI JOE]

Adds more height so it doesn't scrape going on and off boats and transports etc.

The recommended placarded load converted to psi is around the 39psi front and 36 rear, unless you're loaded up in the rear which changes to 39 front and 41 rear.

I just run 39 psi all around. 30-32 psi is too low for a low profile tyre.

Yep, gav is correct, run 39psi all round for general motoring. Look at the placecard in the petrol lid.

[babs]

250 front / 270 rear.

Just out of curiosity, why would you have two different sets of tyre pressures for front and rear? I know that the front will have most of the load obviously because the engine's there. If anything shouldn't the front have higher tyre pressure than the back?

[gavs]

It depends on how the tuning for suspension, damping rates, load carrying, (lack of) ride comfort over uneven roads, braking balance, ESC calibration, Abs calibration etc is setup.

Why higher pressures in the rear? Well for me, I want more grip at the front end of a FWD car and allow the rear to pivot around the front and get "dragged" around the corner. There is a great book on race car engineering which applies to everyday vehicles aslo in regards to tuning the suspension setup in a car called "Tune To Win" by Carroll Smith.

It's a great read and once you read it, you can have a laugh at all those people who think their coilovers are awesome after dropping their car 80mm