What is the optimum tire pressure?

YouTube auto reviewer Savageese owned a mazda 3, changed oil on a brand new car with mazda moly. Sent it in for analysis at 15k miles. Reply from the lab was that sample looked great - next time send it after 18k miles. And most importantly he tracked the 3-still oul looked great. you are not abusing the cx5, 10k is pretty safe on mazda moly. 7.5 k for regular synthetic. Keep in mind he sent the oil sample in for full analysis instead of guesswork. I change every 7k miles. Will switch to 10k soon as engine gets older.

Search for Savageese+vlog 21 to see the video on YouTube.


I do know of one poster on BITOG that goes with 10k oci on his Fords with direct injection and has excellent results based on the uoa. I think the driving habits and style play a big role here. These engines like to run so winding them up so to speak can help with fuel dilution and buildup of carbon. I do that with the CX5 by putting it in manual mode for shifting.
 
Out here everyone goes to Costco, so do I. All their technicians are trained by Michelin. They won't even ALLOW anyone to heckle them to put even 1 psi above what manufacturer recommends. Period. They won't put ANY wheel except the sizes that came with the car - options. I'd go with their recommendation and stick to factory specs.
Also - you walk in and ask them to check the pressure - the 1st thing the guy asks - how long have you been driving today before this request? If more than 15 min., please park .... and then come back after 20 min. please. They won't even check the pressure unless the tire's cold enough!
 
Out here everyone goes to Costco, so do I. All their technicians are trained by Michelin. They won't even ALLOW anyone to heckle them to put even 1 psi above what manufacturer recommends. Period. They won't put ANY wheel except the sizes that came with the car - options. I'd go with their recommendation and stick to factory specs.
Also - you walk in and ask them to check the pressure - the 1st thing the guy asks - how long have you been driving today before this request? If more than 15 min., please park .... and then come back after 20 min. please. They won't even check the pressure unless the tire's cold enough!

That's great but also quite insufficient wrt cool down time! They won't stray from placard due to legal reasons I'm sure- nor should they I suppose. BTW- you roll up @Costco and ask them to check your tire pressure?
Isn't this easier, more accurate(when your tires are fully cooled)- I guarantee you 15-20 minutes is leaving plenty of residual heat in the tires esp the fronts and therefore resulting in your tires being underinflated, nothing huge- but a # or 3 easy I'd bet- plus always good to self-confirm I say:

https://www.amazon.com/dp/ (commissions earned)
 
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Running 36 psi for the daily NYC commute, 38 when heading out to the relatively better out of state roads. I check psi every week or so, and carry 2 gauges and a hand pump in the car (it's also used for my bike and can go up to 140psi). I know they make electric pumps but I need the exercise.
 
I cant believe Im reading this. They spend millions testing vehicles along with the tyre manufacturer. All the different systems are set up for the correct pressure. And yet, so many seem justified in changing them. If they quoted 2psi under optimum would that help? You could then play about and maybe guess it right.

I know that when I ran my 17inch Geolanders at 34psi on my previous CX5 (as recommended) the outers were worn considerably more than the inner. When my tyres were replaced with Falkens my local 4 wheel alignment and tyre centre recommended running at 36psi. On my 2016 CX5 I still run at 36psi and the wear is equal in the middle and sides. This is my experience only, so I can't guarantee the same set up elsewhere.
 
I know that when I ran my 17inch Geolanders at 34psi on my previous CX5 (as recommended) the outers were worn considerably more than the inner. When my tyres were replaced with Falkens my local 4 wheel alignment and tyre centre recommended running at 36psi. On my 2016 CX5 I still run at 36psi and the wear is equal in the middle and sides. This is my experience only, so I can't guarantee the same set up elsewhere.

Exactly my point. I have 29,000 miles and checked 2 weeks back shows remaining wear: 60%. Went to Costco for tire rotation/balancing and they also confirmed same value.
 
That's great but also quite insufficient wrt cool down time!

BTW- you roll up @Costco and ask them to check your tire pressure? Isn't this easier, more accurate(when your tires are fully cooled)

I guarantee you 15-20 minutes is leaving plenty of residual heat in the tires esp the fronts and therefore resulting in your tires being underinflated, nothing huge- but a # or 3 easy I'd bet- plus always good to self-confirm I say:

https://www.amazon.com/dp/ (commissions earned)

Yes, I do roll up and have them check it, once bi monthly. I have Nitrogen in those tires. I have them check it and fill it with Nitrogen if required.

The long story is during winter months, the 15 min. wait is fine. During summer, its insufficient they also confirmed to me. But asking consumers for even bigger wait is also not possible.

I do own a very good tire pressure tool but heck - for me Costco is like 5 min. away.
 
The door sticker recommendation is the best all-around pressure for safety, steering response and tire life. If you deviate much from this recommendation you are compromising one for another. Ed
 
What is the optimum tire pressure? I have a 2018 Mazda CX-5 GT with toyo a36 225/55r/19's The door sticker say 35psi, Than I read stories that 40 is ideal. For those of you who especially have the 2017 CX-5s. What tire psi have you found to be the best?

Any Mazda owner can chime in.
Mazda has recommended a little different tire pressures on CX-5 from different tires and different regions. For the US CX-5 Mazda recommends:

225/65R17 100H 34 psi
225/55R19 99V 35 psi (2nd-gen) / 36 psi (1st-gen)

Like most others, I put 3 psi more than recommended pressure - 39 psi when cold, on my 225/55R19 99V Toyo A23s.

Factory recommendation is only a guideline. It changes and is getting higher when tire design is getting better and can hold higher pressure for better efficiency. If I follow the recommended tire pressure on my 1998 Honda CR-V which is 26 psi, the new replacement tires would be severely under-inflated and wearing the outer tread. After many test and trial by myself, I have to use 35 psi on my CR-V with any modern 51-psi maximum inflation pressure tires such as my current General AltiMax RT43 tires for the best overall performance!

Another issue people havent mentioned here is car manufactures only give one-size-fit-all recommended tire pressure in the US but give different tire pressure recommendations according the load and speed in most other regions such as this one found on my VW Passat:

pic-6981828435756281753-1600x1200.jpeg
 
Nitrogen doesn't expand with heat like normal air (which is the whole point of using it). There will be very little change in psi with N filled tires when they've been driven on
 
Yes, the door frame has a recommended psi, but there is a reasonable range for psi too. PSI goes up/down roughly 1 psi per every 10F change in temperature. With the crazy weather we've been having here, I wasn't letting air out of my tires last week when it hit 79F here in NYC, nor will I be inflating them later this week when it's going to be dropping to the mid-40s.

On nitrogen filled tires... it's nice that places do that, and yes, that will be more stable to temperature variations and leak less, although the air we breathe is already 78% nitrogen. We've got a CX-5, not a Formula 1 race car -- the benefits for us are fairly minor I would imagine.
 
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I was just looking at the 2017 Mazda 6 owner's manual to see what it says about tire pressure and this caught my eye.

US: 19" 92W tires--35 psi front/35 psi rear
Mexico: 19: 92W tires-- w/up to three 165lb passengers, 33 psi front/33 psi rear; @ max load (850lbs), 36 psi front/46 psi rear

Totally different #'s for the exact same tires. I wonder if Mexico requires a more detailed psi breakdown that the US does? It looks like maybe the US #'s are geared towards better mpg
 
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Nitrogen doesn't expand with heat like normal air (which is the whole point of using it). There will be very little change in psi with N filled tires when they've been driven on

Yes it does. Nitrogen is BS. You realize that 78% of atmosphere is nitrogen. So even if you're pumping in medical grade pure nitrogen, into tires you magically vacuum collapsed around your rims....you're only gaining 22% more nitrogen than you have already no matter what you do, so even if nitrogen had no thermal expansion (it does), it would only be a 22% improvement in a perfect world, and more like 5-10% or something in the real world.
 
Some tyre shops put nitrogen in but bulk of dealer service centres etc use air.
 
I run mine up a few but its up to you really just maintain 35 min cold and you'll be fine. I personally wouldn't breach 40 but I'd rather them 5 high than 5 low. Higher pressure will firm the ride up and you may see slightly better fe but also provide somewhat less traction in wet/winter conditions (I switch to 17s on winters) also sharpens steering response..on gen1 with a23 Toyos for 3 seasons I found 38 to be the sweet spot for me but its pretty subjective. See you're in fl so winter not really a concern..you can go up to 40 see how like it and adjust them down from there..

My dealer sold it to me at 38.
 
Its a placebo effect. I absolutely guarantee that nobody but the tyres can detect 2psi variation in pressure. Under inflated will wear the shoulders, increase fuel consumption and adversely effect handling and over inflation will wear the crown and adversely effect handling.

You beat me to it. I'm certain I couldn't tell the difference between 36 and 34. I'm inclined to set it to 38 because its reasonably near the recommended pressure, and I know I won't check it often enough. I'm hoping to average 35 :) , by likely filling to 38 and topping up when its down at 32. I wish we had a discrete pressure reading from the TPMS, rather than just a warning when it is way low.
 
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