44psi, daily drive?

[firefox]

Hi, (done a quick search, didn't find much info)

I just got new 235/45/17 tyres and measured the psi and i thought it was high, i rang the guy where i bought the tyres and he said to keep the tyres at about 44psi.

What psi do you guys use for daily driving and what do you think of 44psi?

With the previous tyres ran between 36 -38psi.

so what psi should i run ?

[siksII]

i find with most tyres that size the car skips around too much and is too edgy when over about 38psi thats where i keep mine.

[Sydneykid]

30 psi cold and 35 psi hot.

[leech_]

36psi warm/hot

[firefox]

30 psi cold and 35 psi hot.

What do you mean by cold? and Hot?

[ferni]

Having them on a high psi is good for wet weather (helps force water out the sides)

having them on a bit lower psi will get a bit more rubber on the ground.

Then again first P.I track day i went to, they recommended if your running street rubber (not stickies) to run 5psi above what tyre rating is... so around 40-45psi on mine.... so who knows.

[predator]

I only run about 32.. too much more feels a bit dodgy to me.. i've always noticed they pump it up to the crappery at tyre places (usually 40psi yeah). Maybe its to account for the average family boat?

[illusiVe]

and the family people who dont check tyre pressures weekly, monthly...anually,...

[WazR32GTSt]

What do you mean by cold? and Hot?

air is denser when cold, and expands when hot

so a pressure of 30 when cold and 35 when hot would be about the same

personally i keep my tyres at 32psi (when cold)... why 32? well my mate's dad owns a tyre shop and that's what he recommends for even wear over the tyre thus maximum tyre life

Warren.

[MYSTR33]

44psi, thought we were goin to be talkin about turbos hahah

[grandmasterb]

44psi, thought we were goin to be talkin about turbos hahah

BWAHAHAHHA i wish i had a 44psi daily driver. Imagine going to work on over 2bar of boost :Pimp2:

[xRHETTx]

40 psi hot, as recommended by the instructor when i went to the Driver Dynamics advanced driving course here in Vic. Improved wet weather handling, tyre wear and feel of the road etc, with a slight loss is grip. If i wanted max grip, id run much less pressure, but the handling would be shit. IMHO

[ferni]

Sounds the same as i was told Rhett

[firefox]

ok thanks

looks like i'll drop the psi a little and test a few different alternatives. Might go back to 38psi which i used before and i liked.

btw. what psi do you guys run at the drags?????????????????

[race_snooze]

i thought it all depends on what profile your tyre was hhmm. As run 265 35 they fell like crap under 38psi

[scathing]

How long have you had them on for? If you literally just got them, you need to run a higher pressure to bead them in. I'd probably leave it for a little while before changing the pressures.

As for what pressure you should run day to day, what kind of tyre are you using? It can make a difference.

However, 44psi sounds way too high, especially for a 45 profile tyre.

Aside from the water evacuation reason given above, there are only 2 other reasons I'm aware of to run high pressure. If you're doing a fair amount of highway cruising, then you want to run them high to lower the rolling resistance (which improves economy and tyre life as there's less friction). The other is to use air pressure to stop the tyre sidewalls from flexing. Obviously with a bigger profile you'll get more potential flex, so you need to run higher pressures to offset this.

However, aside from decreasing your tyre contact patch there's also the issue that the tyres are more likely to overheat. This means you'll get more squirm from the tread block, and drastically reduce tyre life. But, you'll need a sustained load on the tyres to generate enough heat for this to be an issue. I'd hazard to say that, even for most street cruises, a sensible driver will never get their tyres hot enough for it to be an issue.

For day to day driving, if you're on a nice set of street tyres with a reinforced sidewall (or a set of Formula R semi's), run a lower pressure. You'll get more grip and more resistance to overheating, and you let the tyre construction avoid sidewall flex. If your sidewalls are soft, then run slightly more to improve turn-in.

So how much you run is a balance of these factors, which is obviously going to depend on your car and your tyres. Its not possible for anyone to give you an exact number unless they've been in your car. In the end, someone has to do "tyre tuning" to get the pressures right for your rubber and your car. We can only tell you what effect changes will have.

[firefox]

How long have you had them on for? If you literally just got them, you need to run a higher pressure to bead them in. I'd probably leave it for a little while before changing the pressures.

As for what pressure you should run day to day, what kind of tyre are you using? It can make a difference.

However, 44psi sounds way too high, especially for a 45 profile tyre.

Aside from the water evacuation reason given above, there are only 2 other reasons I'm aware of to run high pressure. If you're doing a fair amount of highway cruising, then you want to run them high to lower the rolling resistance (which improves economy and tyre life as there's less friction). The other is to use air pressure to stop the tyre sidewalls from flexing. Obviously with a bigger profile you'll get more potential flex, so you need to run higher pressures to offset this.

However, aside from decreasing your tyre contact patch there's also the issue that the tyres are more likely to overheat. This means you'll get more squirm from the tread block, and drastically reduce tyre life. But, you'll need a sustained load on the tyres to generate enough heat for this to be an issue. I'd hazard to say that, even for most street cruises, a sensible driver will never get their tyres hot enough for it to be an issue.

For day to day driving, if you're on a nice set of street tyres with a reinforced sidewall (or a set of Formula R semi's), run a lower pressure. You'll get more grip and more resistance to overheating, and you let the tyre construction avoid sidewall flex. If your sidewalls are soft, then run slightly more to improve turn-in.

So how much you run is a balance of these factors, which is obviously going to depend on your car and your tyres. Its not possible for anyone to give you an exact number unless they've been in your car. In the end, someone has to do "tyre tuning" to get the pressures right for your rubber and your car. We can only tell you what effect changes will have.

Just got them(done about 250Km) they are

Hankook K104 235/45ZR17 94Y(300km rated) XL(xtra loaded)

just dropped the pressure to 38psi

they are on a r33 with 2 degree camber at the front and about 1 degree at the back.

Will trial this psi for a while. Heard that the tyres take about 500km before they realy start to stick.

[NZM.031]

how big are the rims??

i have stretched 235s over a 9" rim, and i run 45psi. feels nice and tight. bit rough, but so are the coilovers, all depends on what you feel comfortable with and what your tyre wear/depth of wallet is.

i used to have 255s, which were a bit big for the rim, handling has improved immensly with the 235s....i pumped the 255s up to 55psi for a quick run and they still didnt feel solid.

cheers

Linton

[Baz]

You should have it at 44 psi if you would like a large wear mark directly down the middle of your tyre due to the higher pressure.

I would reccomend the same pressures SK described

[scathing]

Just got them(done about 250Km) they are  

Hankook K104 235/45ZR17 94Y(300km rated) XL(xtra loaded)

just dropped the pressure to 38psi

they are on a r33 with 2 degree camber at the front and about 1 degree at the back.  

Will trial this psi for a while. Heard that the tyres take about 500km before they realy start to stick.

When I googled for your tyre, the first hit was 101tires.com's user reviews. Most of them complain that the tyres have shithouse sidewalls, so maybe you will need to run the pressures high.

As an amusing aside, you'll notice that all the reviews by Yank Tank owners (Lincolns, Mustangs, and other cars not exactly reknown for their handling) think they're a reasonable tyre, whereas the people that are putting them onto Euro or Jap cars think they could have defecated on the rim and come up with a better tyre.

Not sure how long it'll take your tyres to run in. However, they won't grip very well for the first couple of hundred kilometres. They use some lubricant during construction to make it easier to remove the tyre from the mould, and then when they spray everything with tyre black (to give it that lovely sheen that all new tyres are blessed with) that doesn't help with grip either.