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Discussion Starter #1
As the subject says really does anyone know what the tyre pressure front and rear should be on a R33 GTST?
 

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Agreed, I think most people here run about the 30 mark all round.

However, reading the the wheel and tyre bible (link here - scroll almost to bottom) that fella, who knows his rubber, goes for the max pressure minus 10% as a good guide.

I'm trying this right now running 36 all round. Fuel seems to be lasting longer but I think I'm losing a little grip on the corners.
 

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That is a cracking link! That guy sure knows his stuff.

I go for 31 all round. Have had no trouble to date.
 

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After following the carbibles guide and info I've now tried several settings, finally opted for 34 & 36, tyres are Toyo Proxes T1-R's.

Aitch
 

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Usually run all mine around 30-32psi,falken FK451's.

By increasing the pressure; more of the centre of the tyre is in contact with the ground making a smaller footprint and less resistance on the road. Causing it to loose grip.- good for drifting!!

By deflating them slightly more of the shoulders will be in contact with the ground making a larger footprint and result in better grip. This helps on the corners alot i reckon.
 

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Unfortunately that theory has a hole in it, todays tyres are special animals, unlike the dollops of rubber of yesteryear. As a result of which you can have two different tyres on the same car and both will require different pressures for optimum performance.

Which is why carbibles ignores anything and everything the vehicles manufacturer says, it's totally irrelevant. What matters is the tyre, so do as the man says, look for the max working pressure and drop 10%, it won't be far out but it will be higher than you're used to on low profiles!

Don't assume for a minute that this will cause the effect mentioned in the previous post, it won't if you use the formula correctly as each tyre model behaves differently, but RELATIVE to the max working/bead seal pressure.

My oldest son has had nothing but trouble with his Audi A8 Quattro Sport, suspension and steering gear faults are a monthly event, the whole front suspension has been replaced twice in 3 years, once under warranty.

Reason? He read the trye pressure from the sticker on the door pillar, but when he researched the matter on todays low profiles he was running way too low at the recommended 32/34, ended up he needed 44/46! But he didn't find this out until he finally cracked a suspension arm..

Aitch
 

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Discussion Starter #9
OMG quite strange to see this message got a reply after 4 years lol Car is long gone but thanks for the replys ppl:)
 

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Wow!! Didn't notice that! lol

And the prize for oldest thread resurrection goes to...

 

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That is a long time ago!!!! Going to try this 10% rule out and see what happens......results to follow.
 

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Right had a look at my tyres and they have two pressures listed on them; By the way my tyre profiles front are 35's and the rears 40's.

The first is that they are not to exceed 40psi when seating the bead in?? Second one states a maximum pressure of 51psi??

Now if this this 10% rule is applied i should run 46psi all round if going by the max pressure indicated. Going by the bedding in the bead pressure i should run 36psi.

To me 46 psi is something you put in a mountaiin bike tyre:screwy: not a car tyre, as air in the car tyre expands under use especially when driven hard.

Upping the tyres to either 36 or 46 psi in my opinion should make for **** handling and make the car more skitish on the corners as there will be less flex in the tyre. This will be most noticible in the wet especially on corners, as like i said before there will be predominantly more of the centre of the tyre in contact with the surface.

Next time it rains up the pressure in the back wheels and go for a normal drive and see what happpens when feeding the power on coming out of roundabouts or corners!!! It should start to slide quite easily............or just try a large carpark so you don't knacker your car.

Atich that situation you describe with the Audi A8 is intresting if not an expensive lesson!! Think i'll try 36psi for a few weeks and see what the difference in feel/handling is like, increased mpg could just be a bonus :cheers:
 

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It's the lower of the two pressure stat's Les, the higher figure is the Max Load pressure formula.

36 psi is correct and will not result in abnormal tyre wear, as the 10% formula is based on the individual tyre manufacturers specs for that tyre, the car is virtually irrelevant, although personal pref's do have a place but the room for compromise is not as wide as some may think, 2 psi max either side of 36 psi.

Whether or not some grip is sacrificed at the optimum 36 psi is for you to determine with your setup, but I wouldn't drop below 34 psi if so.

Aitch
 

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:cheers: Atich, thought about it over the weekend & past few days and figured it out that it must have been the lower rated psi pressure. Since the other post i still haven't had time to pump the air up to 36psi!!- Mad weekends love em:dogpile: :dogpile:

I'll do it tonight, fill up on the weekend and see whats what after a week or so. If it rains and becomes a handfull the rears will be dropped to 34psi to give a squarer tread pattern...............once ive had some fun:boogy: :rofl:
 

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Mine are on 32 or winter time a lil less. Medium quality tyres ( 120 a peice ) and it seems just about right. More than that and the car feels abit skitery and slidee' , less, and I feel like im driving a transit around fully loaded. ( slight exageration ). Just my own thoughts, most likely ANY other thoughts are more appropriate ! :)
 

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.....So far i have done 100 miles with the new pressures 36psi all round. The handling in the dry seems ok. Maybe the increase in pressure is keeping the tyre walls more rigid helping the tyre keep it's shape & grip? The ride is abit more firm but it must be helping the suspension do it's job properly.

Might even get a few more miles between fill ups but haven't done a long trip to see if this is right.
 

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35 is good for a slightly softer ride Les without giving too much away from the overall rigidity, but I found that 36 is better if you lick it a bit on bad roads. For daily cruising I'd go for 35, any lower and it feels less positive and the suspension starts to do most of the work, IMHO of course, I like the taught precise feel and feedback I get at 35 to 36.


Aitch
 

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I've just bought some falken FK452s and there max is 50PSI. So using that quick rule I should be looking to start at 45PSI. Seems very high.
 

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There'll be a lower bead seal pressure quoted somewhere, probably nearer 40psi, so 36 max running pressure using the 10% rule.

Aitch
 
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