DakotaVette

I am trying to figure out what the recommended tire pressure is for my '15 Z51. On the door the sticker says 30 pounds cold, but no warm recommend pressure. The manual doesn't even look like it gives a recommended pressure. I have factory Michelin 19 inch fronts and 20 inch rears. My last Onstar email said my tires were all low with pressures of 26 & 27 on the front and the same on the back. Onstar also said recommend tire pressure is 30 psi front and back tires, but nothing about if that is cold or warm. The actual tires only say max psi of 51. The Chevy service writer couldn't find a warm pressure recommendation because the rides were warm by the time I drove my car over there. The tires do have nitrogen in them. My friends non-Z51 has a warm and cold recommended psi from Onstar and on the door sticker.

Is it really that hard to figure out?

promocop

Just back from Ron Fellows Track Event. The instructors say 30 PSI, F&R when COLD

DakotaVette

Yes, got that much. However, I do not have a nitrogen filler at my house. As a result, the drive over to the dealer heats this tires up so 30psi cold can't be measured until this tires cool off. Not sure how long that would take. Thanks for the post though!

davekp78

Maybe buy a tire pressure gauge?

DakotaVette

Funny. Have several, plus the car's gauge. Maybe you could mail me one of yours that would give the factory psi pressure for warm tires on a Z51?

VNAMVET

My 2014 Z-51 running air, not nitrogen, after warming up, here in FL on a 90 degree day will show 35 psi after a 50 mile trip. My vehicle always starts out at 30 psi, because I check them prior to a drive. If low I'll add air. When the ambient air temp is cooler, checking tire pressure usually shows less than 30 psi.

Tire wear is even on all 4 tires at 17,000 miles. I also check tread depth, which is currently 5/32nds.

DakotaVette

Thanks for the info. The nitrogen is a pain and I have been trying to keep that in the tires, but I think I will give up and just add air at my house to get to 30psi cold. At least that would get it to the starting point.

CP

Nitrogen in tires is a sales gimmick. If you think that nitrogen will affect your tires before you wear out the tires, then you are mistaken. Also, air is 80% nitrogen, anyway.

promocop

True AND the Ron Fellows say the same thing. Useless

Higgs Boson

What are you doing with the car that you are worried about this? Set your tires to 30 cold as recommended and proceed to live your life.

If you are tracking the car then you should be measuring the temp across the tread after a session to determine what you need to do with the pressure, IMO.

If you are just going to work, store, or cruising around, it doesn't matter.

promocop

True

X25

+1 on not wasting time on nitrogen.

For street, it is 30 PSI COLD. For track, most would go back down to 26 PSI or so cold, but it is also highly dependent on the tire. For instance, R888s like higher pressures, while Trofeo R is best at 30 PSI HOT per Pirelli's guidelines.

FYI, if you'd like to conserve fuel at the street, feel free to bump your cold pressures to 32 PSI or even more. It will have minuscule affect on handling for street, I'd bet you wouldn't be able to detect anything, yet would reduce the tire flex, reducing friction. In fact, you could even hit 35s with little impact. The middle of the tire would also wear out a bit faster than the edges, but really, at the street, the differences are small.

jadatis

Car and Tire-makers only give cold pressure advice , because thats the only reliable way to measure.
Cold pressure is when inside tire temp = outside tire temp=and about 18-12 degr C/ 65-68 degr F.
this is when not driven for hours and no sunshine on tires.
Warm , you never know how much it has cooled down already , and severe braking also heats up the tire inside , transported trough the rimms.

When outside temp is colder then 18/20 degr C the cold pressure measures lower , and still save for tires, but you can give higher pressure for better fuel saving and riding.

But when hotter then 18/20 degr C , you better use higher cold pressure , because when it gets colder you will have to low pressure.

Nitrogen filling has only marginal effect on pressure rising or lowering by temperature-chanche , only because Nitrogen in tanks with pressure of 200 barr/??psi, has no water in it. And effect of water is only marginal , about max 1 psi . When Nitrogen is made with a special hose, its only 95% Nitrogen , and probably still water in it.

I am Able to calculate the cold advice pressure ( for that 18 degr C) if you can produce weights on wheels,axles, and max speed you use and wont go over for even a minute.

From tires , I need max load or loadindex,
kind of tire to determine maxloadpressure /reference-pressure/At-pressure,
Speedcode of tire.
Can all be found on sidewall.

Your tires can be XL/reinforced/Extraload, with AT-pressure of 41 psi ( EUR system 42 psi) , 51 is the maximum allowed cold pressure ( at 18/20 degr C) and so thes are different.
But can yust as well be only Standard Load tires with AT-pressure 35 psi ( EUR system 36 psi ).

Hope you got wiser by my answer.

Greatings from a Dutch Pigheaded Selfdeclared Tirepressure-specialist.
Peter

DakotaVette

Thanks for the info everyone. Driving the car on Monday at about 75 mph in 85 degree weather brought the temps to just over 30psi. I always thought nitrogen was somewhat questionable and instead of messing around with it, I am just going to add air to the tires and go from there.

Bill Dearborn

Set the pressure cold. If you are looking for the dealership to add nitrogen when the car is at their shop make sure you know what the pressure is before you leave using a gauge that has good resolution. They are all pretty much the same accuracy but resolution is how well you can read the gauge.

Once you get to the dealership tell them how much nitrogen to add to each tire based on your measurements. Then when they add nitrogen to the tire they take whatever pressure they get and increase the pressure by the amount you told them each tire had to increase.

For example if you measured 27 and told them to raise it 3 psi and when they got around to measuring the pressure they read 31 they would bring their reading to 34. The next morning in your garage if the ambient temp is the same you should see very close to 30 psi on that tire.

When I take my car in for service I tell them never let air out of the tires but if they see a low pressure then they should add air. Some of the lower intelligence mechanics have trouble with this so you may need to explain it to them.

Bill