Simple pressure instructions...

[AliGTI]

Evening all. Yesterday I had my car up on a ramp and noticed my w front tyres are dished in the middle of the tread, suggesting over inflation?? I go by the instruction sticker in the cap. 2.4bar or 35psi. Has anyone else noticed there tyres dishing at this pressure?

[Octoparrot]

Dished in suggests under inflation, dished outwards suggests over inflation. I run mine at the same pressure as you, 18" wheels, and haven't noticed anything like this on mine.

[AliGTI]

Dished in suggests under inflation, dished outwards suggests over inflation. I run mine at the same pressure as you, 18" wheels, and haven't noticed anything like this on mine.

Sorry I should have said they are standard 17" Monzas. When I said dished I mean if you were to hold a ruler accross the width of the treat you would see a gap in the centre of the treat. I think you were describing treat wear to both edges of the tyre?

[grey golfster]

As Octo...
if center of tyre tread, looked at in x-section across the width of the tyre, is "pushed in", then you have been running under inflated.
No idea on relevance of tyre diameter.
someone wiser will be along in a mo...

[pudding]

Which one of the below best depicts your tyres mate?



The pressure for 18s (on the ED30 at least) is 2.6 bar!

I think the factory pressures best suit the original tyres and best fuel economy.  When you change the tyres to a different brand, it's best to play it by ear.  If the centre of the tyre is wearing out prematurely, knock the pressure back a couple of psi and see if it improves.

[AliGTI]

Which one of the below best depicts your tyres mate?



The pressure for 18s (on the ED30 at least) is 2.6 bar!

I think the factory pressures best suit the original tyres and best fuel economy.  When you change the tyres to a different brand, it's best to play it by ear.  If the centre of the tyre is wearing out prematurely, knock the pressure back a couple of psi and see if it improves.

Thanks pudding. Just as I thought mine have been over inflated slightly as the first pic describes my issue. I've knocked them back to 33psi from 35 to see if that helps. Only 2.1mm left on the tread so I'll be buying new ones very soon.

[pudding]

Which one of the below best depicts your tyres mate?



The pressure for 18s (on the ED30 at least) is 2.6 bar!

I think the factory pressures best suit the original tyres and best fuel economy.  When you change the tyres to a different brand, it's best to play it by ear.  If the centre of the tyre is wearing out prematurely, knock the pressure back a couple of psi and see if it improves.

Thanks pudding. Just as I thought mine have been over inflated slightly as the first pic describes my issue. I've knocked them back to 33psi from 35 to see if that helps. Only 2.1mm left on the tread so I'll be buying new ones very soon.

I've found the same with Eagle F1s and Pilot Sport 4s.  The factory pressure is too much!  Wear in the middle like that makes the steering horribly vague around the center and tramlining gets bad too.

[grey golfster]

Which one of the below best depicts your tyres mate?



The pressure for 18s (on the ED30 at least) is 2.6 bar!

I think the factory pressures best suit the original tyres and best fuel economy.  When you change the tyres to a different brand, it's best to play it by ear.  If the centre of the tyre is wearing out prematurely, knock the pressure back a couple of psi and see if it improves.

Thanks pudding. Just as I thought mine have been over inflated slightly as the first pic describes my issue. I've knocked them back to 33psi from 35 to see if that helps. Only 2.1mm left on the tread so I'll be buying new ones very soon.

A picture paints....
Just as well you posted this!

[chigmuss]

Agreed with the above, the factory 35 psi is too much and makes the tyres struggle to grip on standard Ed30 Eagle F1's. I've always stuck to 32 psi and you can feel the difference for only a 10% drop in pressure. Also use a reliable gauge, I have a trusty metal basic job that slides out when reading, some of the garage ones on the air line are notoriously bad (and the cheeky feckers charge 50p too!)

[AJP]

When I was on MPSS I settled on 33psi after a bit of trial and error, more to find a bit of ride quality than anything else.

35+ was quite crashy. Just that 2 pounds less made a huge difference to how the car felt over the usual crap roads at low speed. I didn't notice any negative effects in higher load corners and still hit 40mpg if I really want to (Stage 2 k03).

There's probably a fair variance between different tyres in terms of ideal pressure. The Michelins tend to have a stiffer sidewall than quite a few others (F1s being one).

@AliGTI if you're due new rubber I'd highly recommend Michelin PS4.

[AliGTI]

When I was on MPSS I settled on 33psi after a bit of trial and error, more to find a bit of ride quality than anything else.

35+ was quite crashy. Just that 2 pounds less made a huge difference to how the car felt over the usual crap roads at low speed. I didn't notice any negative effects in higher load corners and still hit 40mpg if I really want to (Stage 2 k03).

There's probably a fair variance between different tyres in terms of ideal pressure. The Michelins tend to have a stiffer sidewall than quite a few others (F1s being one).

@AliGTI if you're due new rubber I'd highly recommend Michelin PS4.

Cheers! That's very informative. When it comes to the finer points of owning a car I'm a bit of a noob. Thank goodness for forums I say.