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Recommended tire pressure on NC

Posted: Wed Sep 18, 2013 3:46 pm
by pdxa4
Hi Brian,

Wonder if you could chime in and recommend good tire pressures for both street and spirited mountain runs.

I have just got new Dunlop Direzza II's, I ended up getting them in 215/45/17 size. And I have them on the stock 17x7 NC wheels.

I was running a weird 225/55/16 size for a number of years on my car, so it it time for something more normal :)

Many thanks

Re: Recommended tire pressure on NC

Posted: Wed Sep 18, 2013 4:27 pm
by Brian
I say start at 30 PSI and then tune to taste. For canyon driving days try a bit more at 32 to 34psi. For long comfortable freeway road trips try lower like 27psi.

Re: Recommended tire pressure on NC

Posted: Wed Sep 18, 2013 6:30 pm
by pdxa4
Brian wrote:I say start at 30 PSI and then tune to taste. For canyon driving days try a bit more at 32 to 34psi. For long comfortable freeway road trips try lower like 27psi.
Excellent Brian, thanks for the recommendations. It gives me a great starting point...

Re: Recommended tire pressure on NC2

Posted: Thu Mar 27, 2014 3:08 pm
by StephenW571
Hi Brian
I know this is rather subjective but what would be a good tire pressure starting point for 235/40/17 on 17x8 Enkie PF01 for
A) comfortable freeway.
And
B) spirited twisty back roads?.

Thks
Steve

Re: Recommended tire pressure on NC

Posted: Thu Mar 27, 2014 4:39 pm
by Brian
Same numbers....for those twisty back roads 32 to 34psi.....but ideal pressure will depend much on surface conditions, lower pressures to max grip on rougher roads. For long comfortable freeway road trips try lower like 27psi.

Re: Recommended tire pressure on NC

Posted: Thu Mar 27, 2014 8:07 pm
by NaregM677
Brian wrote:I say start at 30 PSI and then tune to taste. For canyon driving days try a bit more at 32 to 34psi. For long comfortable freeway road trips try lower like 27psi.
Really? I would have thought just the opposite. I would have figured a higher psi for the freeway (no real bursts of acceleration, cornering or braking) and a lower psi for better traction through the mountain roads, knowing that the heat being put in the tires would increase the psi as well. Help me understand what I'm missing here.

Re: Recommended tire pressure on NC

Posted: Thu Mar 27, 2014 9:19 pm
by Brian
Notice he said "comfortable freeway". If he had said the goal was max MPG...then higher PSI on the freeway would make sense.

As for the canyon roads, 27 PSi might feel a bit sloppy on a good smooth road, allowing sidewalls to roll over....which means the tread is not working for you because the contact patch is rolling off the surface. Adding pressure helps the turn-in response, stabilizes the tire on the rim, helps keep the contact patch on the ground instead of rolling over. That's all true at least on smooth roads...which is why I noted 'but ideal pressure will depend much on surface conditions', because the rougher the road, the lower pressure you need for max traction.

Re: Recommended tire pressure on NC

Posted: Thu Mar 27, 2014 10:55 pm
by NaregM677
Makes sense. I had figured that with psi nearing 34, the tire may be so stiff and sturdy that it may encourage oversteer. Thanks for the explanation!

Re: Recommended tire pressure on NC

Posted: Fri Mar 28, 2014 6:20 pm
by StephenW571
Thanks the advise
:D

Re: Recommended tire pressure on NC

Posted: Thu Oct 18, 2018 7:29 pm
by avera01
Brian wrote:I say start at 30 PSI and then tune to taste. For canyon driving days try a bit more at 32 to 34psi. For long comfortable freeway road trips try lower like 27psi.

Hi Brian,

Will these values be useful for the ND?

I plan on going up to the North Carolina mountains in 2 weeks to drive the Dragon Tail and other local mountain roads. My car is a 2016 GT with stock tires and suspension except for your RoadsterSport SB set to the middle hole and your Wilwood LBBK with the 12.19" rotors.

I normally have the pressure set around 28/29 for local South Florida roads as I find the lower levels more comfortable for daily driving and long runs of 100 plus miles, but on flat smooth roads. I figured I used that level (or a bit lower like 27) for the long highway drive up then change it to suit the mountain roads. I expect air temps to be in the 50s possible warming up a little bit mid day, depending on any cold front shifting down.