Tire pressure

[Mike_TX]

The specs on my Premium call for cold tire pressures of 36psi front and 39psi rear. That's pretty high in my experience, especially on the rears. In the hot Southwest, those tires are going to go to 44-45psi at highway speeds in the heat of summer.

I'm more accustomed to fronts and rears both having the same pressures, and those cold pressures being more in the 33-34psi range. (Note that I do not have the staggered wheels/tires of the GT's.) I also figure the "hard" tires contribute to the thrumming sound over expansion joints on roads.

So, my question is, do you observe the recommended tire pressures?

 

[Kamauxx]

I don't have stock tires. I run mine at 34psi on all 4.

If you don't want to go by what Kia recommends you could adjust them based on the chalk method. You'll probably find you're still pretty close to what they recommend though.

 

[nhcowboy28]

I do with those values warmed up. Not cold

 

[Onno P]

My opinion is that nowadays recommended tyre pressures are higher because of taxes.
Harder tyres bring down the fuel usage and thus the CO2 and thus the extra environmental taxes.

Despite that the 3.3 sold in the Netherlands have already an added tax of 42500€ (48000 US$) on top of the 21% state tax/VAT. The GT2 will cost you 113.000 US$.
With ‘normal’ tyre pressures that would even be higher.

Manufacturers want to sell cars. They do not get a percentage of the taxes and for them it is important to get the taxes as low as possible and thus your tyres as hard as possible.

 

[GenesisG70]

I have a gt2 with 4 michelin tires my door sticker says 35 psi cold all tires, i usually run little higher pressure cuz im cheap want to get marginal better mpg or at least i think im getting.

 

[MisterMac]

The specs on my Premium call for cold tire pressures of 36psi front and 39psi rear. That's pretty high in my experience, especially on the rears. In the hot Southwest, those tires are going to go to 44-45psi at highway speeds in the heat of summer.

I'm more accustomed to fronts and rears both having the same pressures, and those cold pressures being more in the 33-34psi range. (Note that I do not have the staggered wheels/tires of the GT's.) I also figure the "hard" tires contribute to the thrumming sound over expansion joints on roads.

So, my question is, do you observe the recommended tire pressures?

Like Kamauxx, I do not run stock tires. I run 245/40/19's on all four corners. In accordance to the Stinger weight, and the Tire Manufacturer recommended pressure (vs load at 50psi) for my tires, I run 35 psi cold all around. During the El Paso summer heat, the pressure expanded to 39 psi hot. The sidewalls on my Nitto Motivo tires are nicely forgiving, and at this pressure they produced a very comfy ride no matter what the exterior temperature is.

 

[Mike_TX]

My opinion is that nowadays recommended tyre pressures are higher because of taxes.
Harder tyres bring down the fuel usage and thus the CO2 and thus the extra environmental taxes.

Despite that the 3.3 sold in the Netherlands have already an added tax of 42500€ (48000 US$) on top of the 21% state tax/VAT. The GT2 will cost you 113.000 US$.
With ‘normal’ tyre pressures that would even be higher.

Manufacturers want to sell cars. They do not get a percentage of the taxes and for them it is important to get the taxes as low as possible and thus your tyres as hard as possible.

You're probably on to something. Here in the U. S. it's a matter of the car companies trying to meet fuel economy requirements, and expecting that the higher tire pressures will give their cars a slight edge in fuel mileage testing.

 

[eflyguy]

I have a gt2 with three michelin tires

Why only three? What's the 4th one?

 

[GenesisG70]

Why only three? What's the 4th one?

Three? what you mean? As far as I know all sedans have 4 tires...

 

[MerlintheMad]

Despite that the 3.3 sold in the Netherlands have already an added tax of 42500€ (48000 US$) on top of the 21% state tax/VAT. The GT2 will cost you 113.000 US$

???Are you saying that the larger engine is "TAXED" the value of the car's MSRP?

 

[MerlintheMad]

Staggered 19" setup has the door plate recommending 38 psi front 36 psi rear. My recent tires off, tires on, experience at Wheel Werks (as I bought rims and had the OE GT rims powder coated), has me going with what they do: if the recommendation is below 40 psi, they inflate all high aspect ratio tires to 40 psi. Their reasoning is that it gives the tires a little more stiffness and thus protects the rims from potholes and suchlike. Sounds good to me.

 

[POS VETT]

I have a RWD GT with staggered 19" tire sizes and my tire pressures are (starting from LF going clockwise): 43, 42, 37, and 38. Recommended pressure is 36 psi for all 4.

 

[MerlintheMad]

I have a RWD GT with staggered 19" tire sizes and my tire pressures are (starting from LF going clockwise): 43, 42, 38, and 37. Recommended pressure is 36 psi for all 4.

I don't know what you are saying; is this what you discovered? Or this is how you set your psi?

 

[Kamauxx]

I have a RWD GT with staggered 19" tire sizes and my tire pressures are (starting from LF going clockwise): 43, 42, 38, and 37. Recommended pressure is 36 psi for all 4.

Umm...is that on purpose?

 

[POS VETT]

I don't know what you are saying; is this what you discovered? Or this is how you set your psi?

That's how I set the pressures.

 

[POS VETT]

Umm...is that on purpose?

Yes.

 

[MerlintheMad]

Why??

 

[SteveCo]

I go by the door card pressures for my summer 19s, and by the pressures shown in the OM for the winter 18s - and always check/set them cold regardless of what pressure they rise to when hot (the cold pressure recommendations are established with that in mind). No complaints about the performance on either set.

I'm not tracking the car or doing anything that I would consider outside the envelope of what the car was designed for - no reason for me to second guess the engineers at Kia on this.

 

[POS VETT]

Why??

I set them that way to account for the dynamics of corner load. During cornering and braking, the front tires carry more weight than the rears, so the front pressures are set higher (than the rears) to stiffen sidewalls and to reduce sidewall rolling; the rear pressures are increased just slightly to account for a higher average of cornering speed. During acceleration, the front tire pressures are less important; the modest increase in rear is also not that important.

The 1-2 psi difference in side-to-side pressures is to account for the difference in static corner weight. Usually in a mass-produced vehicle, the LF corner carries the most weight followed by RF, then LR, and the lightest at RR corner when there is only the driver in the car.

 

[Kamauxx]

I set them that way to account for the dynamics of corner load. During cornering and braking, the front tires carry more weight than the rears, so the front pressures are set higher (than the rears) to stiffen sidewalls and to reduce sidewall rolling; the rear pressures are increased just slightly to account for a higher average of cornering speed. During acceleration, the front tire pressures are less important; the modest increase in rear is also not that important.

The 1-2 psi difference in side-to-side pressures is to account for the difference in static corner weight. Usually in a mass-produced vehicle, the LF corner carries the most weight followed by RF, then LR, and the lightest at RR corner when there is only the driver in the car.

Do you take a shortcut through the Nurburgring on your way to work?