The Staff of Motorsport Marketing
The Staff of Motorsport Marketing Writer
4/29/22 12:24 p.m.

[Editor's note: This article originally appeared in the November 2009 issue of Grassroots Motorsports.]

As we fine-tune our setups, we often make small tire pressure adjustments to help balance the car and manage tire wear. Small changes can make a difference, and the gap between winning and second place can be smaller still. So how accurate is your tire pressure …

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Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand PowerDork
4/30/22 7:04 a.m.

Hopefully this will get some replies with personal experiences. 

gunner (Forum Supporter)
gunner (Forum Supporter) GRM+ Memberand HalfDork
4/30/22 9:42 p.m.

One time at an autocross I was checking my tires to adjust them and another racer came over with a high end dial gauge and offered to show me how accurate it was. Of course I wanted him to show me, I'm always on the lookout for cool gadgets. The neat part was I had a digital gauge that was the twin to the low cost digital gauge tested here and the readings were identical between his gauge and mine.

livinon2wheels
livinon2wheels GRM+ Memberand New Reader
6/23/22 1:50 p.m.

Love the mechanical dial gauges but they are fragile. I have found digital gauges both fragile and unreliable. I hate battery powered anything when at remote locations like most autocross locations and many tracks. 

kb58
kb58 SuperDork
6/23/22 1:52 p.m.

Well the short answer is "yes", but the real question is, "by how much", which could/may vary widely between brands and measurement method.

J.A. Ackley
J.A. Ackley Senior Editor
6/23/22 2:21 p.m.

Also take care in selecting the right gauge for the right application. I encountered a successful oval-track racer who was struggling mightily. He then got faster. I found out later what went wrong.

He was using a tire pressure gauge intended for trucks rather than race cars, since his regular gauge broke. His pressures were way off. A gauge has a sweet spot for its accuracy. If you're looking to measure tires with pressures around 10psi, a truck gauge won't have anywhere close to the accuracy you need for that range.

MisterJA
MisterJA New Reader
6/24/22 7:56 p.m.

For HPDE days I use a dial gauge w/bleeder valve. After the first session I typically bleed off 6-8 psi of really hot air, probably near 180 F. Any idea how accurate the gauge is at that point? 

PT_SHO
PT_SHO New Reader
6/27/22 2:49 p.m.

In reply to MisterJA :

OOOooo, great question.  I was at Thunderhill for an autocross this weekend.  Afternoon conditions, air 105F, track surface 135+, tire tread surfaces 140+ after a couple of runs.  The air coming out as I was bleeding the tires made it uncomfortable to even be in the way of it!

So here's what you do.  Read off a tire that hasn't been run and is in the shade.  Then bleed off the tire you're interested in.  Then go back to the shade tire and take a reading of the "known" pressure.  If it changed much, there's your answer.  Extra credit: if it changed, then bleed a little, maybe 1/2 psi, through your gauge and see if it cools it enough to make a difference.  YMMV.

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