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Suggested Air pressure for Aftermarket Tires/wheels
Not sure if there is a consensus when it comes to changing tire diameter or the sorts. But going from the stock 245/40/18 at 39psi. Now I'm at 255/35/19 and 295/30/19. Tires just look a little low. Like, was a smidge on one of those rounded curbs that you park on when parking along the street, my tire gave me cause to pause. Looked as if TPMS sensor could be damaged with how low the tire looked under load. Should I bump it up to 40+?
The tire pressure plackard on your driver's door pillar suggests inflation pressure consistent with a smooth ride and other factors. The plackard assumes that all tires are built the same and use the same pressures. But this is wildly false.
As KEY08 notes, you should look to the pressure information on the tire sidewall itself, and be guided accordingly. The assumption here is that the tire manufacturer knows how the particular tire is constructed, and advises pressures that work best for that tire. They anticipate that the tire will be used on a variety of vehicles from light sedans to heavy sedans to wagons to SUVs to light trucks, etc. So, the tirewall pressure discounts the vehicle application and instead notes pressures that are most efficient in grip and longevity for that tire.
I have learned over decades to inflate the tire to 10% (no more than 15%) less than the maximum cold pressure indicated on the tire (regardless of what it says on the door plackard). Some may complain of a slightly harsher ride, which is understandable in many cases. However, IMO, this discipline gives the most even treadwear across the contact patch, and the best treadlife overall.
So, in KEY's example, I would inflate a 50psi tire to 44-45psi, cold. People can inflate to lesser pressures if they want a mushy ride. But treadwear will increase, guaranteed. YMMV.
What is the max pressure listed on the tire? 50?
I would go to 40-41
I'll have to look at the sidewalls and see.
Originally Posted by DFWdude
This has been discussed numerous times...
The tire pressure plackard on your driver's door pillar suggests inflation pressure consistent with a smooth ride and other factors. The plackard assumes that all tires are built the same and use the same pressures. But this is wildly false.
As KEY08 notes, you should look to the pressure information on the tire sidewall itself, and be guided accordingly. The assumption here is that the tire manufacturer knows how the particular tire is constructed, and advises pressures that work best for that tire. They anticipate that the tire will be used on a variety of vehicles from light sedans to heavy sedans to wagons to SUVs to light trucks, etc. So, the tirewall pressure discounts the vehicle application and instead notes pressures that are most efficient in grip and longevity for that tire.
I have learned over decades to inflate the tire to 10% (no more than 15%) less than the maximum cold pressure indicated on the tire (regardless of what it says on the door plackard). Some may complain of a slightly harsher ride, which is understandable in many cases. However, IMO, this discipline gives the most even treadwear across the contact patch, and the best treadlife overall.
So, in KEY's example, I would inflate a 50psi tire to 44-45psi, cold. People can inflate to lesser pressures if they want a mushy ride. But treadwear will increase, guaranteed. YMMV.
yes it's been discussed but I see such wildly differing opinions out there. Plus it was late and I was headed to bed so I didn't state that I knew most of what you said already. However, the 10% info I didn't know about at all. Thanks for that. My tires tend to warm up to about 41 psi after 14miles. At the start of the ride they sit at about 38. Also, not sure how to air up tires cold when I have to drive somewhere to air them up lol but thanks for the info.
yes it's been discussed but I see such wildly differing opinions out there. Plus it was late and I was headed to bed so I didn't state that I knew most of what you said already. However, the 10% info I didn't know about at all. Thanks for that. My tires tend to warm up to about 41 psi after 14miles. At the start of the ride they sit at about 38. Also, not sure how to air up tires cold when I have to drive somewhere to air them up lol but thanks for the info.
Air up your tires within a mile from home and you are good. Failing that, air up the tires just before returning home, let the tires cool overnight, then check (and bleed off excess) pressure the following morning (when "cold"). If you have an emergency compressor in your trunk, you can use that at any time the tires are cold.
Using the previous example, the 50psi maximum is also a cold pressure, meaning that on the road the pressure will build to 3-5psi over 50psi. Perfectly fine per the tire manufacturer.
And yes... regarding this topic there are wildly differing opinions.
Air up your tires within a mile from home and you are good. Failing that, air up the tires just before returning home, let the tires cool overnight, then check (and bleed off excess) pressure the following morning (when "cold"). If you have an emergency compressor in your trunk, you can use that at any time the tires are cold.
Using the previous example, the 50psi maximum is also a cold pressure, meaning that on the road the pressure will build to 3-5psi over 50psi. Perfectly fine per the tire manufacturer.
And yes... regarding this topic there are wildly differing opinions.
this is precisely what I needed thank you. Currently at the dealership, will check everything once he's good and done with!! Thanks for all your info. Checked my pressures on the way here. They actually started at 36 and wound up at 41 but upon exiting the highway and hitting the side streets, they somehow cooled to about 39-40.
SIDENOTE: I see you're either from DFW or live in DFW. Any other members in the area? Anyone do any kind of meetups/gatherings? (COVID Notwithstanding)
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
the optimal pressure for a given tire size depends on the actual load. lower profile tires need higher pressures as they have less sidewall. high speed driving also calls for higher pressures.
High speed driving always require lower pressures than street speeds... I start at 30lbs front and 32lbs rear .. .. after a 30min track session in the c63 ‘507’... tire pressures are over 45lbs... Anything over 40lbs... 507 feels like it’s running on bowling *****!...
High speed driving always require lower pressures than street speeds... I start at 30lbs front and 32lbs rear .. .. after a 30min track session in the c63 ‘507’... tire pressures are over 45lbs... Anything over 40lbs... 507 feels like it’s running on bowling *****!...
wow, that’s crazy. I start at 27 in the GT350 and end up running hot around 32, which is optimal. That’s with Michelin Pilot SS.
+6,000 track miles on the 507 running Michelin Cup2s , the 4Ss and Pirelli P Zero Trofeo Rs... seems the softer the tire compound... the greater pressure gains... go figure. Currently running the Cup 2s ... Bring that GT350 to VIR sometime!
+6,000 track miles on the 507 running Michelin Cup2s , the 4Ss and Pirelli P Zero Trofeo Rs... seems the softer the tire compound... the greater pressure gains... go figure. Currently running the Cup 2s ... Bring that GT350 to VIR sometime!
Just curious...if you had to describe briefly how the 4S performs....what do you think?
My opinion: Very good performance street tire, great in the rain ... Highly recommend them!... at least for the C63.... The 4s are ‘ok’ on the track...
SIDENOTE: I see you're either from DFW or live in DFW. Any other members in the area? Anyone do any kind of meetups/gatherings? (COVID Notwithstanding)
There are several members in the Dallas / Fort Worth area.
Several years ago, we held gatherings at Texas Motor Speedway during their annual open track night. That brought out 6 members one year. But since then, nothing, sorry. I don't think TMS holds the track nights anymore, and everybody is so busy doing their own thing.
There are several members in the Dallas / Fort Worth area.
Several years ago, we held gatherings at Texas Motor Speedway during their annual open track night. That brought out 6 members one year. But since then, nothing, sorry. I don't think TMS holds the track nights anymore, and everybody is so busy doing their own thing.
Damn that sucks to hear. Would love to meet up with others. Guess I'll have to go back to my roots. Cupcake meet(don't judge lmao) one even we had several years back....had about 700 cars show up
+6,000 track miles on the 507 running Michelin Cup2s , the 4Ss and Pirelli P Zero Trofeo Rs... seems the softer the tire compound... the greater pressure gains... go figure. Currently running the Cup 2s ... Bring that GT350 to VIR sometime!
No that makes perfect sense, softer compounds=higher friction coefficient, higher friction=more heat, more heat= higher pressure gains.So a low pressure tire will heat up more and retain more heat than a correctly aired tire.
LCG is correct on this one.
Last edited by pierrejoliat; May 5, 2021 at 08:11 PM.
I fill my tires with an expensive, high-performance, high-tech, specially formulated 78/22 Nitrox blend just below the manufacturers "Don not exceed" pressure.
Now that's funny! Me too! I also use about 1.2% Argon...LOL
Last edited by pierrejoliat; May 5, 2021 at 08:14 PM.
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