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Tire's and psi

3622 Views 11 Replies 7 Participants Last post by  PaulKim
I'm curious as to what tires and psi everyone is running. I recently got a set of new tires and am starting to play around with tire pressure. With my setup right now I'm facing some mid corner exit understeer. To combat understeer, should the rear tire pressure be over or under inflated?

My current setup for my 2014 Mazda 3 Hatch:
- Federal RS-RR 235/40/18 F & R
- 35psi front and rear hot (too high?)

Alignment setting:
- 0 toe, -3F -2R
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I'm curious as to what tires and psi everyone is running. I recently got a set of new tires and am starting to play around with tire pressure. With my setup right now I'm facing some mid corner exit understeer. To combat understeer, should the rear tire pressure be over or under inflated?

My current setup for my 2014 Mazda 3 Hatch:
  • Federal RS-RR 235/40/18 F & R
  • 35psi front and rear hot (too high?)
Alignment setting:
- 0 toe, -3F -2R
This is cornering on street or track? In either case you are likely setting the pressure too high. Definitely if you are talking track or autocross.

If you are street driving it is going to be hard to find an ideal tire pressure because when you cruise to work your PSI won't increase much. But when you do spirited driving it will increase. So 35psi is fine for commuting but probably goes to 40+ with spirited driving and definitely over 40 if autocross or track. The only way to know is check your pressure. Buy a quality pressure gauge (I like Longacre brand). Pull over when your tires are hot and check the actual pressure.

You want to aim for a cold pressure that when heated up is the pressure you want hot, which can only be done by checking hot pressures and using that information to adjust cold pressure.

On the street I just put 33psi cold and don't go crazy because I also have street tires.
Your tires are more performance oriented and you have good camber so your tires will heat up even more.

TLDR: get a tire pressure gauge and check your pressures hot, adjust your cold pressures to a spot where when the tires heat up you get the psi you like. 35psi cold is too much for your driving it seems.
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