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Discussion Starter · #1 ·
This has probably been asked before, but here goes...

I have a 2012 S60 T5. I replaced the original Michelin MXM4 215/50R17 tires with Conti DWS06 tires of the same size. The sticker on the door pillar says to inflate to 38 psi for all 4 tires. The tire shop inflated the Contis to 34 psi. When I called them about this they said that is the recommended pressure for these tires for cars "like mine". I was under the impression that any brand tire should be inflated to the pressure on the sticker. The shop said that pressure only applies to the factory tires. Are they correct or should the Contis be inflated to the pressure on the sticker?

Thanks,
Kevin
 

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Inflate the tires to the pressure on the sticker. Granted, 34 psi would probably be fine too, if not a little light as it's pretty close to where the TPMS warning will trigger. My TPMS light went off this week and all four tires were at 32 psi. I hadn't been driving the car that much and temps that morning were in the low 20's.
 

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+1 -- you really only need 38 if the car is heavily loaded (passengers + cargo), or driven at sustained high speed in hot weather. I run 34-36 with no issues.
 

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This has probably been asked before, but here goes...

I have a 2012 S60 T5. I replaced the original Michelin MXM4 215/50R17 tires with Conti DWS06 tires of the same size. The sticker on the door pillar says to inflate to 38 psi for all 4 tires. The tire shop inflated the Contis to 34 psi. When I called them about this they said that is the recommended pressure for these tires for cars "like mine". I was under the impression that any brand tire should be inflated to the pressure on the sticker. The shop said that pressure only applies to the factory tires. Are they correct or should the Contis be inflated to the pressure on the sticker?

Thanks,
Kevin
Inflate to the sticker. The sticker is for the cars performance in handling, braking etc, not the tire.
 

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I find 38 too much, usually keep at 35-36.
Yep, apparently Volvo has 38 on just about all S/V60 tire sizes, which is strange. My V60 sticker has the same 38 psi for 235/40-19's and 235/45-18; is it for the EPA MPG stats? I would agree with your 35-36 psi recommendation for a more civil ride.
 

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Inflate to the sticker. The sticker is for the cars performance in handling, braking etc, not the tire.
Certainly overkill for that size tire. I've never seen such high psi recommended for that size tire. This has to be for bumping EPA test numbers.

Food for thought: I had new 19's put on my car recently by the dealership, and they didn't follow the sticker's 38 psi, inflating only to 35 psi.
 

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Most Volvos (including my '07 VR) used to have an 'optional' pressure of 34-35 on the sticker with a recommended/full load of 38-39. Now because of fuel economy, liability and TPMS constraints (most tire monitoring systems can't handle an 'optional' pressure) they just stick with the one, which is also 38 on my '16 V60 RD.
However, that same V60 came nitrogen filled (scam) new from the dealership last week at 34.5 all around. Most dealers and tire shops will fill only to the old 'comfort' level because they get fewer complaints that way.
P.S.: Keep my VR Michelins at 37.5 front and 38 rear but filled the new V60 to 38 all around (with 'air' which is only 76% nitrogen.)



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Discussion Starter · #9 ·
Thanks for all the replies. I'm going to increase the pressure to 36 psi and see how the ride and handling is.
 

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Two points to remember:

1. For every ten degrees change in temperature, the PSI will vary by one pound. And tires will all leak air slowly (I've found that in two weeks I usually lose 1 to 1.5 PSI).
2. The wear of a tire will depend upon the PSI, so if you want your tires to have a long life, check the wear pattern on the tires periodically. Increase the PSI if the outer edges are wearing more than the center, and decrease if the center is wearing more than the edges.
 

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Thanks for all the replies. I'm going to increase the pressure to 36 psi and see how the ride and handling is.
36 is too much if you ask me, but it really depends on the tires - there's a calculation based on the tire rating/max load and weight of the vehicle... that's if you want to be precise.

My 18in RE-11s require 34 based on the calculation I'm referring to.

n
 

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35 PSi is a perfect sweet spot between Load/Comfort..

Try 35 and see if it works for you.. Mines perfect at 35.
 

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Discussion Starter · #13 ·
npn, can you share the calculation?

At 36 the ride is a bit rough, but the handling (under steer) improved over what it was at 34. I'll lower them to 35 tomorrow and see what that feels like.
 

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And tires will all leak air slowly (I've found that in two weeks I usually lose 1 to 1.5 PSI).
That sounds highly unusual to me. I could go for months if not the ambient temperature changes. In fact, a leak of this rate would make me start looking for a cause... You see this on all four corners?
 

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That sounds highly unusual to me. I could go for months if not the ambient temperature changes. In fact, a leak of this rate would make me start looking for a cause... You see this on all four corners?
Tire Rack: "All things being equal, a tire's inflation pressure will go down by about 1 psi every month. This means that if air isn't added for two to three months, the tire's inflation pressures will probably be 2 to 3 psi low." The more you drive, the more likely you'll lose more air in the same time period (my daily commute is about 70 miles both ways, highway driving). With seasonal variations, of course it can be more as the ambient temperature drops (my car is garaged, and the outside temp in the winter is lower by at least 10-15 degrees). Just taking the gauge off the valve will lose some air, and a digital gauge in a pump will show about .5 psi low from the removal and air lost from what goes into the hose. I've found over my ownership of several cars, with summer and winter tires, I can be about a pound low after two weeks. I use high-quality gauges. The higher the PSI, the greater the measured loss. And it's all four tires, not any one.
 

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I wasn't doubting what you wrote, just thought it sounded a bit high. 1psi a month is more in line with what I'd expect intuitively. We put about 1k per month, so about 1/2 as much as you do I guess, which seems to roughly match the drop rates as it turns out. I did write that I could go for months, but now I'm thinking that I probably never actually go that long between checking the pressure on the primary car, and the second car just isn't driven all that much...
 

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npn, can you share the calculation?

At 36 the ride is a bit rough, but the handling (under steer) improved over what it was at 34. I'll lower them to 35 tomorrow and see what that feels like.
This is the calculation based on my set of tires of Bridgestone Potenza RE-11 Tires 215/45R18 and my car.

You can do yours, and if you want post the specs here, I'll help:

max load: 1,356 lbs
max psi: 51
car weight: ~3,600 lbs (car weight + 1 passenger, your car could be different)
each tire: 900 lbs

weight per tire / max load * max psi

(900 / 1356) * 51 = 34 psi

You can get more creative and do the math for each set of tires as the front of the car is usually heavier (?)

n
 

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I understand what you're doing, but I wonder if there are other variables, such as contact patch dimensions. For my '13, Volvo specifies 2 lbs less pressure for the optional (wider) tires (I don't know if the max psi is the same for both sizes).

***

As to the original question, that tire shop obviously punted when they gave their explanation for not using the pressure on the tire placard. Lazy slobs who obviously ignored the specs.

The only good explanation I ever heard, in this case for overinflating by 2 psi, was from a Hyundai dealer who told me he did it because cars usually came in with underinflated tires.
 
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