Need All-Season Tire Recomendations

⋯。Ill just list the relevant ones for the CX-5 which are P-Metric SL and XL.

SL is Standard Load and is rated at 35 psi (240 kPa)
XL is Extra Load and is rated at 41 psi (280KPa)
All tires we've discussed here are SL tires. That's why I said you believe 35 psi is the maximum load pressure.

P-Metric is an old US tire standard which's only used in the US on some tires.

Yes there're many tire standards world wide, that's why the confusion.

And you still didn't answer the question on why all car manufactures use higher than 35 psi for heavier load? Again physics say tire pressure and load carrying are in direct proportion, that's why car manufactures are always recommending higher tire pressure for heavier load and faster speed, as long as the maximum inflation pressure allows. Maximum load pressure definitely is not set at 35 psi. Besides, why we want anything more than 35 psi to double the load carrying capability at the maximum load of 1,764 lbs. / 1,709 lbs. and in fact we only need ~900 lbs. load carrying for each tire?

And yes, the range of tire pressures are to get an optimal contact patch but the factory recommended tire pressure, especially the "one-size-fits-all" approach in the US, may not work for non-OE tires.
 
Same information? Tire rack has SL max load at 35,Discount Tire has 36. Not a big deal really,but it is different. Discount Tire would/will never touch my car,but that’s a story for another day.

All in all,it doesn’t matter what the articles say,the way you’re dissecting them isn’t correct,nor is running the tires at 35psi. Most tires aren’t running that these days,but of course you can. Regardless,I’ll take a slightly overinflated tire over a slightly under inflated one anyday,well unless I’m on a wet and sloppy racetrack.
This's so true! Many nowadays still believe higher tire pressure is not safe and would be more easily to cause a blowout. But in fact it's the opposite. Lower tire pressure is generating more heat, hence the blowout.

Besides, the air will leak out gradually from tires. The temperature and weather change also makes the tire pressure lower than the last time you checked if you don't do it often. That's another reason I'd like to keep the tire pressure a little higher than recommended psi.
 
Right we’re nowhere near the max load anyway so in my opinion that’s moot anyway. There are cars recommending lower than 35. I’ve owned a few lately.


These recommendations aren’t to be able to support the load. It’s to get the right contact patch and ability for the tire to flex.

Also there has been a trend to lower profile tires which do run higher psi. For example on my GTI the OE recommendation is 38 psi. And some cars like a S4 is 41 psi I think.

Also, our CX-9 has 19” factory and it’s recommended at 35 instead of the 34 on the 17”.

Really my main point is that running the pressure recommended by the manufacturer isn’t *incorrect* just because your replacement tire can handle more. There are advantages but also *disadvantages* to higher pressure. I do suspect Mazda is going for comfort probably.

A good example is in my MKV the dealer was always setting them at 38 instead of 34 and I noticed reduced grip. I personally liked 35 and didn’t have any issues.
 
This's so true! Many nowadays still believe higher tire pressure is not safe and would be more easily to cause a blowout. But in fact it's the opposite. Lower tire pressure is generating more heat, hence the blowout.

Besides, the air will leak out gradually from tires. The temperature and weather change also makes the tire pressure lower than the last time you checked if you don't do it often. That's another reason I'd like to keep the tire pressure a little higher than recommended psi.

Ugh here again higher to a point. Not just higher is always good and has no disadvantages. That’s plain false. It has pros AND cons. Your mileage may vary.

I will agree with you under is dangerous.

I think where we are really butting heads is that the OE recommendation is under. I’m saying it’s not and you’re saying it is.

Also yea air leaks temperature changes ect. That’s why you should check monthly and adjust as needed.
 
In the US, the psi on the door jamb tag is supposed to be good for up to the max vehicle load. Some countries make manufactures show psi #'s for half and full loads. Take a look in the owners manual and you will see the difference between US #'s and those in Mexico.

US
P225/55R19 99V
35psi front/35 psi rear

Mexico
P225/55R19 99V
With up to 3 75kg passengers (about 500lbs): 36 psi front/36 psi rear
At max load: 38 psi front/42 psi rear
 
Couple of questions.

I'm at 68.5k miles now. Should I look at getting an alignment done now that I am getting a new set of tires? I got my current set back at 18.5k miles. Any suggestions on where to get that done?

And with these H-speed RT43's, what is a good PSI for it? I want to be sure to tell DT to air them up to whatever that should be. 17-inch tires, btw.

It seems silly to me to not at least get the alignment checked when installing new tires. Especially at 68k miles
 
In the US, the psi on the door jamb tag is supposed to be good for up to the max vehicle load. Some countries make manufactures show psi #'s for half and full loads. Take a look in the owners manual and you will see the difference between US #'s and those in Mexico.

US
P225/55R19 99V
35psi front/35 psi rear

Mexico
P225/55R19 99V
With up to 3 75kg passengers (about 500lbs): 36 psi front/36 psi rear
At max load: 38 psi front/42 psi rear

IMHO, its region based. Mexico is a lot warmer.
 
⋯ I think where we are really butting heads is that the OE recommendation is under. Im saying its not and youre saying it is.
You just answered the question yourself ⋯ :)

If thats the case why is the US recommended psi at max load different than Mexico?

Based on tire pressure recommendations for gen-2 CX-5 225/55R19 99V tire listed above, our single tire pressure recommendation is low even comparing to half-load / normal condition recommendation in Mexico!

And different tires would require different tire pressure for optimal performance, especially when the size and specs, such as the maximum inflation pressure / maximum load pressure, are different from OE tires.
 
You just answered the question yourself ⋯ :)



Based on tire pressure recommendations for gen-2 CX-5 225/55R19 99V tire listed above, our single tire pressure recommendation is low even comparing to half-load / normal condition recommendation in Mexico!

And different tires would require different tire pressure for optimal performance, especially when the size and specs, such as the maximum inflation pressure / maximum load pressure, are different from OE tires.

1 psi doesn't really make much of a difference. Most air gauges have an error margin larger than that.

It probably has to do with different govt mpg requirements
 
Mexico is a lot warmer than Arizona? Then why Canada doesn't get lower recommendation? :)

In that case I'll just pull out the whole 'Merica card again.

On a serious note I tend to go with 36 PSI in the summertime. I don't know if its a myth or not but when I first moved out here I noticed a lot of car's tires blown out. My brother told me it was from people over filling their tires + the heat.
 
I still disagree with you that Mazda is recommending everyone drive around under inflated.
My main point still is if the maximum inflation pressure on tires is the maximum load pressure. Since OE 225/65R17 100H has the maximum load at 44 psi, hence you need more air pressure on a tire with the same load index and the maximum load at 51 psi in order to get optimal contact patch for the same weight carrying.

And I said it before, most one-size-fits-all tire pressure recommendations in the US is low based on tire pressure recommendations in other regions and from my past experience. Tire blowout issue on Firestone tires from Ford Explore many years ago was due to low factory recommended tire pressure. My 1998 Honda CR-V has 26 psi recommended tire pressure but for its RT43 with 51 psi maximum inflation pressure I have to use 36 psi to get an even wear. I use 39 psi instead of 36 recommended psi on my CX-5 too.
 
My main point still is if the maximum inflation pressure on tires is the maximum load pressure. Since OE 225/65R17 100H has the maximum load at 44 psi, hence you need more air pressure on a tire with the same load index and the maximum load at 51 psi in order to get optimal contact patch for the same weight carrying.

And I said it before, most one-size-fits-all tire pressure recommendations in the US is low based on tire pressure recommendations in other regions and from my past experience. Tire blowout issue on Firestone tires from Ford Explore many years ago was due to low factory recommended tire pressure. My 1998 Honda CR-V has 26 psi recommended tire pressure but for its RT43 with 51 psi maximum inflation pressure I have to use 36 psi to get an even wear. I use 39 psi instead of 36 recommended psi on my CX-5 too.

Can you provide proof? Also the pressure they were recommending then was bellow 30..... not the stuff we see today. Also tire technology hasn’t stood still. We’re just going to have to agree to disagree. I feel the manufactures are more qualified than you are for pressure recommendations on their vehicles. I also think your logic that a tire that can hold more pressure needs more pressure to hold a load is flawed at best.
 
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In that case I'll just pull out the whole 'Merica card again.

On a serious note I tend to go with 36 PSI in the summertime. I don't know if its a myth or not but when I first moved out here I noticed a lot of car's tires blown out. My brother told me it was from people over filling their tires + the heat.
Your Tourings have 34 psi recommendation and you added 2 more psi.

I believe more blowout tires in your area is due to people under-inflated their tires by not checking tire pressure more often, which will generate more heat than an over-inflated tire. Of course over-inflating a tire with lower maximum inflation pressure rating is dangerous in your area too. That's why I'm always looking for replacement tires with higher 51 psi maximum inflation pressure rating which has larger safety margin on tire pressure.
 
Can you provide proof? Also the pressure they were recommending then was bellow 30..... not the stuff we see today. Also tire technology hasnt stood still. Were just going to have to agree to disagree. I feel the manufactures are more qualified than you are for pressure recommendations on their vehicles. I also think your logic that a tire that can hold more pressure needs more pressure to hold a load is flawed at best.
Based on Michelin's spec sheet in post #72 the maximum load pressure is the maximum inflation pressure. The physics say tire pressure and load carrying are in direct proportion.

For OE Yokohama Geolandar G91A 225/65R17 100H its maximum load is 1,764 lbs. @ 44 psi maximum inflation pressure.

For General AltiMAX RT43 225/65R17 102H its maximum load is 1,874 lbs. @ 51 psi maximum inflation pressure.

At 44 psi. RT43 can't carry 1,874 lbs. rated maximum load, but at 51 psi, it will. On a CX-5, optimal contact patch can't be the same having the same weight on both tires with the same recommended tire pressure @ 34 psi. You need more psi on RT43 to carry the same load with similar contact patch.
 
yrwei, do you agree that if your tires are set to 36 psi, and then you load 1000 lbs into the car, the tire pressure will still be 36 psi?
 
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