c5creech

Having 3 C5s and 1 08 C6 Vert...I have had a considerable amount of experience with the on-board tire pressure sensors on these Vettes. However, I always backed-up the DIC tire pressure read-outs with a manual pressure guage. Well, after years of dedicated service...mine has finally died... It was one of the high-end guages with the dial and the pressure release...

Any of our Forum Vendors have a really bullet-proof tire guage for sale? Anyone have any experience with the "digital" guages?

I know, in the scheme of things (ie: cams, exhaust systems, intakes, superchargers, etc.) this is a very simple part...but, these days...it can save your tires and a bunch of money on gas...not to mention make your Vette handle to factory specs...

By the way, anyone have an opinion on "cold tire pressure." It's now 25degrees on the beach here in North Carolina with snow...3 days ago it was 60 and the tires were fine...now I'm getting a 27 pound reading on the front tires... From an engineering standpoint...anyone know what the "mean air temperature" is for the "cold tire pressure" base-line?

Thanks for your help!

Vette_DD

Whatever temperature you're going to be driving in. I typically have to add 2-3 lbs. about 2-3 times during the fall & winter as it gets colder & colder.

C-INRED

The 'baseline' is whatever the current temperature is where the car is being operated.

LarryMJones

If you consider the volume of the tire near constant the temperature pressure ratio is as follows. (Assume volume remains fairly constant at these small pressure changes.)
P1/P2 = T1/T2

Remember to use 460 degrees Rankine as a base for temp plus temperature in farenheit, and 14.7 psi for pressure conversion to actual pressure.

Example: T 2 - 70 degree outdoor temp = 530 Rankine
T 1 - 30 degree outdoor temp = 490 Rankine

P 1 - 70 degree starting pressure is 30 psig + 14.7 = 44.7 psia

Solve for P - 2
P - 2 = 41.32 absolute - 14.7 equals 26.6 psig

Tire will loose aprox 3.4 pounds between 30 degree day and 70 degree day sitting in your driveway.

If you know your running tire temp you can calculate the pressure at the elevated temp. Or if you read your pressure readout you can calculate your tire temperature at speed.
LJ

MADinAK

but only understood the 14.7 equals 26.6 psig part.

In looking again, maybe I don't even understand that part. Doesn't 14.7 equal 29.4 PSIG?

johnodrake

I have a $16.95 Accupressure digital and a $40 Longacre dial. The digital is easier to use and just as or more accurate.

LarryMJones

Subtract the 14.7 conversion to absolute gauge from the calculated absolute pressure to get back to what you read "gage pressure".

The calculations must be made with absolute temperature and absolute presure.
Conversion as follows:
degrees farenhait + 460 equals absolute temp.
Psig (g for gauge) = 14.7 equals absolute pressure

Use the absolute numbers in the equation and calculations. Then convert the answer back to farenheit or gauge pressure psig by subtracting the conversion units.

This asumes the tire volume is constant, volume does vary some but not much with a few just a small change in pressure. If you want to fill the tire 100% with water at 30 psig and then lower it to say 27 psig by draining water out you could actually measure the small volume change per pound increase, but thats a lot of trouble. Just assume the volume stays aprox the same and use the perfect gas formula above.
LJ

K9KUZ

Same here and

TEXHAWK0

I use a dial type gage from Accugage, and it about as accurate as you could expect from a hand held gage.
http://www.ghmeiser.com/

http://www.getagauge.com/DialTireGauges.cfm

davekp78

My digital (Campbell-Hausefield) only reads in 1/2 pound increments. I like my dial bleed down type better. If yours breaks, you only need to get a new pressure gauge from Grainger or like places.

vetdude

I have all three - digital, dial, pencil. The only one that differs on pressure readings is the DIC.

Montanajim

Use a Moroso dial gauge, myself. The DIC always registers 3 PSI less than the gauge, any gauge. Checked the Moroso against my old Draeger and a made in USA pencil gauge, all register the same. I like the Moroso best because of the air release capability. The DIC and the TPMS system are a waste of time and money for anyone who cares about the machine he's driving.

NS

Wayne O

I most often use a Craftsman digital gauge....it was approximately $35.00. It has some complex functions and is guaranteed accurate within 1% +.

Doug Rippie Motorsports was selling a nice analog/dial gauge a while back for around $40.00 or so.

Boomer111

Digital gauges do not seem to like cold weather. I'll stay with my Acc -guage by Meiser. Never have liked the pencil style.

cclive

I'm a Meiser guy also, have 3 of them. Quality, made in USA.

9C1

I have 6 Meiser gauges -- an analog one for each of the cars, and a spare digital. A plus for me is that their factory (the oldest one) is in Posen, IL. Not too far away from me. Free repairs and calibration, and the nicest people you could ever hope to meet.

Never Say Never

Good to know this about the Craftsman. I may have to get one someday.

I did find 2 guages that cost $5 at Walgreens. They both read within .5 of each other and the same as the dic. I think I just got lucky.

LMB-C6

I have an Accu-Gage dial gauge with the flex hose, a Sears digital, and a no-name pencil style.

I used to think that the pencil style gauges were worthless, and that price = performance and accuracy. WRONG.

If you want an excellent comparison of gauges read this article:

LINK

BEZ06

My feelings about the sensors and TPMS are just opposite of yours, at least if you're driving on runflats.

I've had several punctures in my runflats and at slow speeds or while driving straight I would never have known I lost pressure without the DIC telling me.

A year ago I picked up a screw in a parking lot. I drove a couple miles to the interstate and settled down to cruisin along at 80 or so for a couple minutes until I got a "ding-ding-ding" and a message of low tire pressure in the LR. There was absolutely no handling feedback and if I had driven the next 30 miles to my exit and taken it at the usual speed I take the off-ramp, I'm sure I would have ended up in the guard rail when the tire lost traction when the sideload built up.

I care a great deal about the machine I'm driving, and I'm glad I have the sensors to tell me need-to-know info that you just can't feel when driving on runflats.

I like them on the track in my Hoosiers as well - it's nice to be able to see the pressure changes in individual tires during a track session.

Bob

GCD1962

What's more important than even an accurate pressure, is to ensure that each tire is running the same pressure. Even a gauge slightly off will still allow you to give each time the same pressure.