I feel dumb for even asking

[SSpeckerwood]

I just got my 17" LTZ wheels put on last night. The tires I'm running are Capitol sport UHP in 205/50/17, 93WXL all season.

The question I have is about tire pressure. On the tire they say max pressure is 51 psi and max load at that pressure is 1433lbs per tire. My dealership set them all to 39 psi.


Is this pressure to low for this tire?

 

[LazyLion]

That is the same size as the Hankook tires that came on my LTZ. The sticker on my door calls for 35 psi.

 

[SSpeckerwood]

But doesn't say 35psi on your tire, just like on the door?

 

[SteveSonic]

Sidewall tire pressure guidelines tell you the maximum load you can carry on a tire at the maximum inflation pressure. The manufacturer's tire pressure recommendation (on the B pillar sticker and in the manual) are a compromise between ride quality and tire longevity for the given stock tire, which is sometimes designed/specific to the car. Your only real penalty for increasing the pressure over the car manufacturer's recommended maximum is a rougher ride, but you'll gain fuel efficiency of 1-2 MPG's. Hyper-milers often take their pressures higher than the tire manufacture's recommended max.

 

[Papasonic]

The stock Hankook tires on the Sonic LTZ have a 1235 lbs at 44 psi rating on the sidewall. GM engineers have determined that 35 psi is the optimal pressure for traction, performance, and ride quality, using the oem tire. There is a 7 psi difference between the Capitol Sport tires max rating and the Hankook oem tires max rating. Therefore one could conclude that 35 psi in the Capitol Sport tire would indeed be too low; 39 psi still seems low, relative to the tires max rating. You have presented a question that is difficult to give a definitive answer, due to using a different load and speed rated tire on your Sonic.

Papasonic

 

[SSpeckerwood]

They were at 39 psi. I aired them up to 45. We'll see how it rides tomorrow. So far it feels better around town.
I'll know better once I get it on the highway.

 

[esymr2]

I would bring them back down to 35-39. Your new tires can go to 51 because they are extra load rated at 93W. Stock tires in that size are rated 88H. I doubt that you would be loading the car more than the stock tires can handle.

 

[wingman]

45 is a little too much IMO. But over-inflating tires can help fuel economy. I usually run 33 in mine.

 

[DeltaMP]

Don't forget that air expands when it heats up. So on the highway your PSI may jump a bit, especially if your some where hot (like Texas).

 

[SSpeckerwood]

I drove on 45psi today. Seemed very responsive. A tad harsh, but at 39psi it didnt feel any softer. I'll run them at this pressure for awhile. Thanks for the input. These 17 handle so much better than the stock 15

 

[Danny5]

One issue of raising your pressure without increasing the weight is abnormal tire wear. An overinflated tire will bulge at the middle, between the sidewalls, causing faster tire wear in the center vs. the edges.

The higher pressure is meant for when you load your car. So if you were running 2400lbs of load in your car, you could increase tire pressure to compensate.

I would recommend running 45psi in the front, 37ish in the rear, during competitive driving events, but not for daily driving.

 

[SSpeckerwood]

One issue of raising your pressure without increasing the weight is abnormal tire wear. An overinflated tire will bulge at the middle, between the sidewalls, causing faster tire wear in the center vs. the edges.

The higher pressure is meant for when you load your car. So if you were running 2400lbs of load in your car, you could increase tire pressure to compensate.

I would recommend running 45psi in the front, 37ish in the rear, during competitive driving events, but not for daily driving.

So what would you recommend for daily driving then?

 

[Danny5]

So what would you recommend for daily driving then?

38 to 40lbs max.

 

[SSpeckerwood]

I'll try 40 in the front and 38 in the rear then