What is ideal pressure for 18 wheels?

[mordeaur]

Hello,

I own a 1.4 TSI FR with 18'' 30/1 alloy wheels. Pressures printed inside petrol cap as 32/29 for light weight. My weight is around 120 kilos(i'm a bit fatty, i know, and I generally use my car on my own. According to seat dealer 32/29 is way too low for 18 wheels and it should be fixed around 36/33. I'm totally confused and can't find ideal pressure for wheels. I've been trying lots of combinations such as 32/29, 33/30, 34/31, 35/32 even 35/35 and non of them feels right. I really need a clarification on this wheel thing. Also I'm confused about front and rear pressure difference. As far as i've searched some people has pressures printed as 33/31 which is 2 psi difference for front and rear yet mine says it should be 3 for single usement. What is this unstable info?

I'm already gratefull for any help and thanks for your time. Sorry about my bad grammar. Have a nice day everyone.

 

[AndyN]

Depends who you ask. Had a random browse of a hyper mile forum and they're all reckoning they go 5 over the stated max on the tyre which would be 55PSI :-s I always have mine higher than the dealers recommend, usually about 40PSI give or take. Still well under the max for the tyre.

 

[sixysix]

Seat technicians build the car to the spec needed and the weight is then calculated then give a figure to what the tyre pressures should be for that particular vehicle.
Are you really going to take a dealers word that the company he works for is wrong even though it's printed inside the cap of your, and every other Seat Leon out there?

If yours says 32/29 then stick to that or there abouts. Mine has 33/31 for a light load which is a higher psi than your vehicle because I assume that the diesel lump in my car weighs a bit more.

It's mainly about the weight of a car as to how much pressure the tyres will need.
Under inflating is obviously not good, but over inflating a tyre by a large amount is just as bad and will kill the tyre just as fast as having an under inflated tyre.

You will probably get a better mpg with an over inflated tyre but pointless if the tyres wear out faster, plus the steering will be light, car will feel "loose" and I assume will make it easier to invoke aquaplaning in the wet at speed?

A BMW X5 might need 55 psi in it's tryes due to the weight, but a family hatchback like the Leon does not

 

[AndyN]

I didn't recommend inflating his tyres to 55PSI. I said that some hyper mile forums advocate it. I always keep my tyres higher than the dealer recommends though. My last car that I just traded in still had 5mm of tread with even wear after 3 years of use and they were at 41 all round.

 

[sixysix]

I didn't recommend inflating his tyres to 55PSI. I said that some hyper mile forums advocate it. I always keep my tyres higher than the dealer recommends though. My last car that I just traded in still had 5mm of tread with even wear after 3 years of use and they were at 41 all round.

I know matey
But some do and its just bonkers to even consider it! lol
pretty impressive about the 5mm after 3 years, although how many miles did they do in that time?

Nothing wrong with 41 though if it's needed, mine were at that pressure from the dealer and I only realized yesterday so dropped them down as I don't carry bodies in the boot every week! lol

 

[AndyN]

Not many.. That's why I said 3 years haha. It had done 14600. All but 30 with me. I take my frustrations out on work vehicles where I get paid to drive fast!! They get through tyres every few weeks.

No boddies but too much junk in mine. Should really empty it.

 

[sixysix]

15k with 5mm left is amazing! what were they made of? ABS plastic!

Don't tell me, You are a white van man during the day then?

 

[AJ]

As six says, best thing to go with the recommended figures for the car. The recommended pressure for my18s on my old 2.0 TDI A3 was 42/36.....massive difference between front and rear! But I kept the pressures as recommended and the car was great to drive.
Also thanks for the prompt, I haven't checked the pressure of my tyres either! Will do so tomorrow

 

[sixysix]

As six says, best thing to go with the recommended figures for the car. The recommended pressure for my18s on my old 2.0 TDI A3 was 42/36.....massive difference between front and rear! But I kept the pressures as recommended and the car was great to drive.
Also thanks for the prompt, I haven't checked the pressure of my tyres either! Will do so tomorrow

I am betting between 39.5-41 all round lol
Steering weight feels better and the back end is less skippy now it's on 33/31

Some cars just weigh a bit more but surprised about 42 on an A3!

 

[AndyN]

15k with 5mm left is amazing! what were they made of? ABS plastic!



Don't tell me, You are a white van man during the day then?

Haha I don't know... But I hope my new ones are as good!

Might as well be! My main motor is a heavily modified yellow LWB sprinter, and second is a smoking fast Octavia Scout. If I say I always have a little smile on my face when I see the dreaded double flash at night does that give it away?

 

[sixysix]

Haha I don't know... But I hope my new ones are as good!

Might as well be! My main motor is a heavily modified yellow LWB sprinter, and second is a smoking fast Octavia Scout. If I say I always have a little smile on my face when I see the dreaded double flash at night does that give it away?

Have to be a paramedic then I assume,
Very noble and worthy career there

No offense, but I hope I never meet you and your sprinter! lol

 

[AndyN]

You'll know if you do. It usually smells of burning rubber and clutch. Or a part will fall off outside your house. Or it'll break down outside your house. They're the opposite of cherished!!

 

[AJ]

I am betting between 39.5-41 all round lol
Steering weight feels better and the back end is less skippy now it's on 33/31

Some cars just weigh a bit more but surprised about 42 on an A3!

I was surprised too when I first saw the figures and though it was a misprint, lol. I guess the older CR Diesel block must have been a lot heavier than these new ones.

The Leon drives well atm so be interesting to see what the pressures are and if they are wrong, the car could even feel nicer to drive

 

[Crafoo]

Unless you've got a different wheel/tyre combination than the car came with as standard then go by whatever is printed on the inside of the fuel cap.

 

[mordeaur]

Thanks for all your replies. I decided to go with 32/29 for my 18 wheels after all.

 

[DeanC]

I run 35/32 after a bit of trial and error.

 

[mordeaur]

I run 35/32 after a bit of trial and error.

Doesn't it printed as 33/31 on your cap since car has diesel engine? Why there is 3 psi difference while it should be 2? According to latest posts, it should be 2 difference for diesel, 3 for fuel.

 

[sixysix]

Doesn't it printed as 33/31 on your cap since car has diesel engine? Why there is 3 psi difference while it should be 2? According to latest posts, it should be 2 difference for diesel, 3 for fuel.

As Bruce Hornsby would say "That's just the way it is". God I feel old now!

The pressures are a recommendation so you can adjust a little without having uneven tyre wear later on down the line

Mine feel much better now with correct pressure, not light and airy like a magic carpet and steering is more direct with a better feel.

The other thing that might come into play with the pressures, is whether you have a space saver in the boot or not as it will add a bit of extra weight to the rear end

 

[sixysix]

The Leon drives well atm so be interesting to see what the pressures are and if they are wrong, the car could even feel nicer to drive

Mine was not bad at 41 and fine when driving normally, it was when you pushed on and got a bit spirited on some A/B roads, then you could feel it was not so sure footed through the bends.

Much better now though and would be better still if we got some dry roads! lol

 

[DeanC]

Doesn't it printed as 33/31 on your cap since car has diesel engine? Why there is 3 psi difference while it should be 2? According to latest posts, it should be 2 difference for diesel, 3 for fuel.

32/29 printed on mine. I just prefer it a bit higher - somewhere between normal and fully laden.