Max PSI on my tires says 40

carandetc

Just realized my Bridgestone tires have on the side " do not inflate over 40PSI" warning. But I regularly see on the TP monitor when driving a while 41 in city and 42 on highway. Cold tires are around 37.

Is that a typo? or do they mean cold tire pressure should be 40 max.

thanks

kyfdx

carandetc said:

Just realized my Bridgestone tires have on the side " do not inflate over 40PSI" warning. But I regularly see on the TP monitor when driving a while 41 in city and 42 on highway. Cold tires are around 37.

Is that a typo? or do they mean cold tire pressure should be 40 max.

thanks

What does your door placard say about recommended tire pressure? 40 PSI seems awfully high for a normal tire pressure, but then again, I don't know what car you have.

The 40 PSI max on your tires is tire specific, not vehicle specific. It is not a guide for what PSI your car should have (but, it shouldn't be exceeded)

capriracer

I think what is being referred to is the small print on the sidewall that says do not using more than 40 psi WHEN MOUNTING a tire. That's another set of small print that gives operating limitations for load and inflation pressure that are different.

Plus all inflation pressures are COLD pressures - except when they are specifically referring to pressure buildup. Tires can and will build up pressure in use due to heat and tires are designed to withstand normal pressure buildup.

kyfdx

@capriracer‌

Thanks for your input... I thought 40 PSI seemed awfully low for a MAX tire inflation pressure..

stever

capriracer said:

I think what is being referred to is the small print on the sidewall that says do not using more than 40 psi WHEN MOUNTING a tire.

Well, that's a new one on me.

Tire info is just too hard to come by; I have trouble just reading the brand much less the fine print stamped into the sidewall. Figuring out the manufacturing date is too big of a struggle, I always ask the tire guy to tell me when I get a new set.

carandetc

kyfdx said:

What does your door placard say about recommended tire pressure? 40 PSI seems awfully high for a normal tire pressure, but then again, I don't know what car you have.

The 40 PSI max on your tires is tire specific, not vehicle specific. It is not a guide for what PSI your car should have (but, it shouldn't be exceeded)

Recommended is 35 (door placecard) which is awfully close to the max 40 and very easy to exceed.

capriracer said:

I think what is being referred to is the small print on the sidewall that says do not using more than 40 psi WHEN MOUNTING a tire. That's another set of small print that gives operating limitations for load and inflation pressure that are different.

Plus all inflation pressures are COLD pressures - except when they are specifically referring to pressure buildup. Tires can and will build up pressure in use due to heat and tires are designed to withstand normal pressure buildup.

Yes 40 PSI is on the small print on the sidewall, took me a while to realize.

So max 40 PSI 2.75 kPa refers to max COLD pressure?
While driving they end heating up to 41, 42

Actually it says literary:
"NEVER EXCEED 40 PSI 275 kPa TO SEAT BEADS"

so I dont have to worry. although as said before I cant remember where it said to put extra 6 PSI for highway,

@stever , Yes it is so difficult to read it.

I guess not even the dealer can read it because when I picked up the he inflated the tires to only 32 psi. should have 35, but my other car he inflated to 35 and should have 32.

Now that I have TP monitor on the dashboard in car, its not such a big deal but my favorite pump has a faulty gauge so before I realized I used to over inflate my tires to 60, and got scared after I checked it with my little gauge.