tyre pressure

[ecl]

heya

on the door panel thing, it saids the tyre pressure should be 35 psi

this is for the stock GTT rims 17x7.5 jj

however, as i have just recently upgraded to 18x8's

should i still use 35 psi? anyone with 18's use something different?

car is a gtt but i think they should all be the same right?

just wanted to make sure as not to blow up my tyres lols

[Busky2k]

Stick with 35 for starters and then play around with the pressures a tad. Like add 2 psi and take it for a drive and see how the steering response/comfort degredation changes. There is no golden rule for tyre pressures as it depends on the tyre, driver, car and driving style. However I wouldnt see the need for exceeding the mid 40s on the street.

[blind_elk]

The tyres fitted to the rims should have a spec for optimum pressure.

As a rule of thumb, run the fronts 2 psi higher than the rears - it helps to reduce understeer.

[madmurf]

Tyre Pressures are one of the miss understood settings on a car.

The facts are as follows.

1 The tyre recommended specs on the car door are OEM for a comfortable ride on stnd rims and OEM tyres.

2 Most car drivers run too soft a tyre which can cause blow outs because of tyre wall flex.

3 If you run at the tyre wall recommendation for a comfortable ryde then your tyre will wear out faster and use more petrol. Ask yourself what would the tyre company want.

more tyre sales or less.

Try letting your tyres down to 15 PSI and push it down the road. It will twice as hard compared to it at 38PSI.

4 Rule of thumb for a high speed handling is 6 to 10 PSI harder than recomended

I run 40 PSI on my 17" 235 45 tyres.

5 Max tyre pressures on side of the tyre walls is for a USA standards and is crap.

You can safely pump a tyre up to 200 PSI. At 300 the ryim will probaly give way before the tyre goes pop. Think about a thin Bicycle tyre it can over 40 psi no probs.

Happy to talk about other facts and BS told by mechanics

:headspin: :headspin: :headspin: :headspin:

[T0nyGTSt]

I've been recommended 38-40 psi on 40 series low profile tyres as long as you realise what this does to road comfort.

T.

[ecl]

thanks guys

yer, i let it up to 38

could immediately feel the difference

felt like i was on balloons lols

but it sure felt alot easier to go uphill

[knore]

My 17" 235/45 fronts are on 45psi

and back 245/45s are 45psi

max pressure stated is 50psi

[ecl]

45? wow, might up mine a bit more

also, i've just upgraded from my stock gtt rims (17x7.5jj) to 18x8's

would there be a need to recalibrate the speedo?

[The Dan]

I run 45 psi all round and this is on stock 32 gtst rims 16". I get like 45 000 k's outta my tyres coz I set up my own Wheel alignments and check tyre pressures regularly.

As for what madmurf said...no disrespect but that is wrong.

You will not pump a tyre to 200 psi. a passenger tyre will pop at around 85-90

a performance tyre will pop at around 100

a LT tyre around 120 or so. But they can go earlier. You'll know when she blows too...coz if you're within 10 metres of it at 80 psi, you won't be able to hear anything for around 5 minutes.

There is no way the tyre will outhold a rim.

[The Dan]

45? wow, might up mine a bit more

also, i've just upgraded from my stock gtt rims (17x7.5jj) to 18x8's

would there be a need to recalibrate the speedo?

Not if you haven't altered the overall rolling diameter of the wheel and tyre.

it depends on the difference in tyre size..

If you give me the before size (17") and the after size (18") then I will be able to tell you how far out your speedo will be if at all.

[madmurf]

GTR Killer

I was involved in a new tyre testing about 5 years ago at race track with Bridgestone.

They did a demo of inflating a tyre to over 200PSI and the steel rim buckled first.

I dont know which tyre you had blow but it would have not been a Steel belted radial.

If you dont believe ring the manufacture not your local tyre Git and check it out.

Cheers

[HypeR33]

ecl,

as stated by madmurf if you have changed rims, forget about the tyre pressure plaque on the door. That is for factory fitted units only.

I have 18" x 9' or 10' cant remember now, but they r running 35 series. When I had then fitted they recommended 38 psi for normal day to day driving

[ecl]

ok cool

thanks all

its a relief if the tyres wont blow up... i was scared of it goin "POP" at the petrol station lols