see, back in the day, without all these fandangled gadgets, we never knew we might maybe have a problem possibly.

which you don't. just wait till the weekend when it cools off.

 

44 psi maximum inflation on tirerack.com for the SR/A's, but that'll have a safety factor. They won't blow at 45 psi.

 

Do you reccommend lowering to 30 PSI to get a better safety margin?

 

Tires will heat up due to friction from driving. If you look at the sidewall you'll see that the max inflation is 44psi cold and are designed for the increase in pressure from the heat cycles.

 

Thanks for the advise, as i m worry about driving it for vacation in the summer, as temp will likley hit 90 & above, that might push psi into the 50s??
Currently, I m using a set of Firestone Affinity tires 215-60-17 on 17" silver Compass wheels. The sidewalls of the tires reads "Never Exceeds 40 psi to sit beads
(I think, have to check later to make sure) no idea what that means?

I put away the Goodyear SRAs, as i like the silver rims better, & the ride likely smoother with the Firestones. Anyone knows if the PSI is the same for both the Goodyears & Firestones? The Owner's Manual doesn't specify & point to the sticker on the driver side door for the info, as my Pat came with Goodyears, the sticker spec 35 psi. Will the Affinitys be different?

 

First thing in the mornings here, it's about 80°. Tire pressures read 34-35psi.
By my drive home when it's 105° or more, they will read 39-40psi.

Without doing the math (I'll pretend that I actually could), it looks like 25° rise in air temp equals about 5psi rise in tire pressure. Unless the air temp gets to be 150° or so, you're probably safe with a cold reading of 35psi as recommended.

 

I'm pretty sure the firestone affinitys say 32 psi cold on the sticker in the door (i'll check) but I start with about 33-34 and have noticed the increase in our heat wave.
EVIC is reading 31 - 32 C outside temp on my drives.
Remember though that bad stretch of weather last June where Lions training camp was basically a washout

EDIT - Door panel sticker for the affinitys does say 32 psi
i am showing 268-275 after driving for some distance divide by 6.9 gets = 39 - 40 psi as well and the tire does say max 44psi/300kpa cold. I think we are OK, i will check this weekend based on more seasonal temps coming our way.

oh by the way - LOVE that Choice of Deep water blue

 

I'm pretty sure the firestone affinitys say 32 psi cold on the sticker in the door (i'll check) but I start with about 33-34 and have noticed the increase in our heat wave.
EVIC is reading 31 - 32 C outside temp on my drives.
Remember though that bad stretch of weather last June where Lions training camp was basically a washout

Thanks Dave, as i just check the tire pressure at 700pm, that is after the Jeep is parked for more than 5 hours, it is still at 40 psi. (with tire gauge)
I figured that the Affinitys might be spec at a different psi compare to the Goodyears. Once the temp cools down, likely after 900pm, i will adjust it down to 32-33 psi

 

Mine definately say 45 PSI on them. I've been running 40-45 for the last year and a half. Mines an '07 though- different tires?

 

I don't think so. The FDIIs are always Goodyear SRAs, 215-65-17 the other 17" option on non FDIIs has always been Firestone Affinitys (as far as i can tell). As I bought a set of spare wheels/tires/sensors from a Compass owner with the Affinitys 215-60-17 as i have no info on the PSI spec, I pumped it to the Goodyear reccommended 35 PSI, but over the last few days with very hot weather 81 degrees yesterday, the monitor showed PSI at 42, made me a bit worried.

BTW, last evening with the weather still warm & tire pressure at 40 PSI, i dropped it to 36 PSI, with the cooling overnight, i figured it will be around 32-33 in the morning.

 

Before there was TPMS (about 95% of my life), we checked the tire pressure about once a year, or when a tire "looked low". Never (well, rarely) suffered a catastrophic failure. Seems to me, TPMS just makes us paranoid about tire pressure.

 

that was my point exactly!

although I guess it's a good thing, seeing how TP can affect milage

 

FWIW
EVIC reported 19 C today and tire pressure of 248 kpa / 6.9 = 36 psi
still this pressure was lower (234) when morning temps were about 10 C

 

if all you are going to do is do is paved driving, switch from air to nitrogen then. nitrogen doesn't heat up as much and normally expands about 1 psi in about 85 degree weather. it cost me like $5/tire to do. the loss rate of pressure should also be less since there is not so much expansion and contraction.

if off-roading you can always bring the pressure back up with air mixed in but you lose the benefit of the nitrogen. i have mine filled to 37psi at 85 degrees. they never go over 39psi while driving.

 

That's a good idea, as over here Costco tire dept uses Nitrogen if you buy tires from them. Sure can get a deal as a member.