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Discussion Starter · #1 ·
Not to sound stupid, but what is the correct tire pressure for summer, and how do you make that happen?
Background: Up here in NY, it's been freezing cold at night, hot during the day for a couple months, now it's just hot all day and night. When I check the tire pressure during the day, it's 80 degrees out plus sun, so it's probably alot warmer than that sitting parked in the driveway(direct sunlight).
When I filled up all the tires, it was still in the warm/cold weather phase, and all were set at 32lbs....the car hadn't been driven or anything when I checked the tire pressures.
But now that it's hot out, when I haven't driven at all, the pressures are reading closer to the 40lbs range. I let some air out of all the tires so now the gauge reads down around 35lbs without having been driven...but the tires look kind of squishy.
I don't mean to be all OCD, and I'm getting my brake pads replaced tomorrow so I'll have them check the pressures...but I was wondering if you guys could comment on this phenomenon and how you test actual correct tire pressure in hot weather.
I'm literally sitting at home today, working online...and I'd rather be doing it by the lake, but I'm afraid to drive too far in case I mucked up the tire pressures. I haven't checked the pressures today because I was so freaked out by yesterday's pressure readings... so again, any advice you could offer would be greatly appreciated!
Thanks, Marissa
(2008 RAV4...I think the mid-range model, not the entry level and not the one with all the bells and whistles)
 

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No worries on the potential OCD - once we see big swings in temperature it happens a lot. In the summer type months, I set my pressures when the temp is around 20C or about 70F. Of course as the day goes on the heat will increase the pressure, and the heat from the road will add even more to it. Set at the number on the door (should be 32) and drive away. I keep an eye on the treadwear patterns of my tires too, and will make adjustments to the pressure as needed. It’s a challenge right now due to the wild swings.


2012 RAV4 Base FWD. Upgraded to large front brakes and 3rd row rear springs.

Link to SAE J2807 test description
 
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Discussion Starter · #3 ·
No worries on the potential OCD - once we see big swings in temperature it happens a lot. In the summer type months, I set my pressures when the temp is around 20C or about 70F. Of course as the day goes on the heat will increase the pressure, and the heat from the road will add even more to it. Set at the number on the door (should be 32) and drive away. I keep an eye on the treadwear patterns of my tires too, and will make adjustments to the pressure as needed. It’s a challenge right now due to the wild swings.


2012 RAV4 Base FWD. Upgraded to large front brakes and 3rd row rear springs.

Link to SAE J2807 test description
TY for that Foryota, I appreciate it! I've been trying to be an adult and take care of all kinds of things on my own, and this is a new puzzler for me.lol I think 70-degrees F is the coolest it gets at night right now...at the moment, it's 95 degrees but that's not in the sunlight, so it's prob higher. I'll check them tonight or in the early morning when it's cooler...
((on the plus side, I did manage to refill my refrigerant yesterday so my a/c is nice and cold again....yay for the little successes!lol))
 

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TY for that Foryota, I appreciate it! I've been trying to be an adult and take care of all kinds of things on my own, and this is a new puzzler for me.lol I think 70-degrees F is the coolest it gets at night right now...at the moment, it's 95 degrees but that's not in the sunlight, so it's prob higher. I'll check them tonight or in the early morning when it's cooler...
((on the plus side, I did manage to refill my refrigerant yesterday so my a/c is nice and cold again....yay for the little successes!lol))
Good stuff! I assume you used one of the home refill kits - was it just the “freon” can or did you use the sealant can also? I ask because if you used the sealant and then later need to have a garage do work on it, the sealant can gum up their machine, and the cost to repair could end up on you (in the thousands).

As for pressures, I tend to keep my rears at 35-36 cold during the summer, primarily due to towing for yard work and camping. I do need to keep an eye on the tread pattern for wear on the inside or middle part of the tread. Easy to manage when paying attention.


2012 RAV4 Base FWD. Upgraded to large front brakes and 3rd row rear springs.

Link to SAE J2807 test description
 
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Discussion Starter · #5 ·
Good stuff! I assume you used one of the home refill kits - was it just the “freon” can or did you use the sealant can also? I ask because if you used the sealant and then later need to have a garage do work on it, the sealant can gum up their machine, and the cost to repair could end up on you (in the thousands).

As for pressures, I tend to keep my rears at 35-36 cold during the summer, primarily due to towing for yard work and camping. I do need to keep an eye on the tread pattern for wear on the inside or middle part of the tread. Easy to manage when paying attention.


2012 RAV4 Base FWD. Upgraded to large front brakes and 3rd row rear springs.

Link to SAE J2807 test description
Ty for that!! I’m saving it so I won’t forget.
Yes it was just refrigerant. I watched a vid of how to do it and bought the Freon/refrigerant that comes with the reading gauge. Mine was low when I tested it, so I shook the can like he showed, and kept shaking and filling until it was well into the green and the compressor kicked on and the engine speeded up(or whatever all that activity is—it sounded just like the vid). And when I checked the cabin in was nice and cold... I’d had a bunch of work done over the last 6months or so, so I figured everything was mechanically ok, and it was just not getting cold like it used to...It took several days tho to ‘accept the knowledge’lol bc I wanted to believe it was just really hot and the a/c just couldn’t keep up like when it was newer.lol I watched the vid tho and knew it was a cheap and easy fix to refill it—I’d paid to have it done on my last car b4 this suv, and it was over $100 just to refill —so I wanted to try since it looked easy as pie...sure enuff, yes, a successful, non-anxiety producing repair accomplished.lol
 

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Ty for that!! I’m saving it so I won’t forget.
Yes it was just refrigerant. I watched a vid of how to do it and bought the Freon/refrigerant that comes with the reading gauge. Mine was low when I tested it, so I shook the can like he showed, and kept shaking and filling until it was well into the green and the compressor kicked on and the engine speeded up(or whatever all that activity is—it sounded just like the vid). And when I checked the cabin in was nice and cold... I’d had a bunch of work done over the last 6months or so, so I figured everything was mechanically ok, and it was just not getting cold like it used to...It took several days tho to ‘accept the knowledge’lol bc I wanted to believe it was just really hot and the a/c just couldn’t keep up like when it was newer.lol I watched the vid tho and knew it was a cheap and easy fix to refill it—I’d paid to have it done on my last car b4 this suv, and it was over $100 just to refill —so I wanted to try since it looked easy as pie...sure enuff, yes, a successful, non-anxiety producing repair accomplished.lol
Sounds good. Just be aware that a system won’t get low or run out - it’s supposed to be a sealed system. Gone are the days of my 1997 Corolla which still had the factory fill 12 years and 300,000 km later (and still ice cold!) so you do have a small leak somewhere. The good news is that there is some dye in the system now (and I think from the factory) so you can find the leak with a black light. It shouldn’t be too bad, but certainly something to monitor. Remember that the can you used has some dye also so there will be some residue where you connected to the system.


2012 RAV4 Base FWD. Upgraded to large front brakes and 3rd row rear springs.

Link to SAE J2807 test description
 
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... so I wanted to try since it looked easy as pie...sure enuff, yes, a successful, non-anxiety producing repair accomplished.lol
You never addressed the reason why the AC system was low ... there's a leak somewhere.

It's easy to add, difficult to find and repair the leak. Too many idiots on YouTube offer the band aid solution, but never address the leak.

If you have dependents or remotely care about the environment, get the leak fixed. You'll be dead and gone as the climate gets worse. Your dependents will be living in it.
 

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I'm a little OCD about pressure and I try to adjust it at the low end of the temperature range for the season. That usually means I do it in the morning on an average day. I also avoid doing it when the sun is shining on the tires, so I don't end up with more pressure on one side of the car.

Realistically though, there's a range of acceptable pressures. Don't worry too much about a few lbs.
 

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Discussion Starter · #9 ·
Sounds good. Just be aware that a system won’t get low or run out - it’s supposed to be a sealed system. Gone are the days of my 1997 Corolla which still had the factory fill 12 years and 300,000 km later (and still ice cold!) so you do have a small leak somewhere. The good news is that there is some dye in the system now (and I think from the factory) so you can find the leak with a black light. It shouldn’t be too bad, but certainly something to monitor. Remember that the can you used has some dye also so there will be some residue where you connected to the system.


2012 RAV4 Base FWD. Upgraded to large front brakes and 3rd row rear springs.

Link to SAE J2807 test description
oh that kinda sucks. I thought it was just low from the fact that it's a 2008...evaporation?lol Hopefully this will hold a while--and I bought the bigger bottle so I can add more if I have to. Just need to get through a few more months until I can trade it in.
 

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You sound a little "OCD" about tire pressure! I always put 35lbs in mine at the beginning of each season and leave it at that. As mentioned before (wishK)?, don't check TP in direct sunlight or even if it was sitting in the sun before. Also, I don't trust what the shops put in tires. I always check mine after returning from a shop and more often than not have to readjust the TP. I also recheck lugnut torque if they remove any wheels. Several times I've had to use a length of pipe to loosen and re-torque them when I get home.
 
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