This past July I purchased a new Toyota Prius c. The manual and door post suggest 35psi front tires and 33psi rear tires. My dealer, at 5000 mile did 33psi for all 4 tires, told me that what they always used. For winter I purchased 4 Michelin X-ICE snow tires. the dealer also did 33psi for all 4 of these tires. I questioned the service department (manager) about this and she told me their statistic studies showed 33psi on all 4 tires to be best for my area (NW Pennsylvania). My thought is 35psi front and 33psi rear makes more sense, due to relative weight of front versus rear of car. Any thoughts on the matter, and/or whose right? - appreciated.
I would go with the Toyota recommended pressure. You could check with a local Toyota corporate representative to see if they have the same info the dealer does.
If your winter tires are the same size as your stock tires, use the manufacturer’s recommended pressure. If not, adjust accordingly. For a second opinion, talk to the customer support people at tirerack.com They are very helpful. A difference of 2 psi will not make much of a handling or wear difference.
Thanks.
Is the 3psi differential in this situation critical. How accurate are tire pressure gauges anyway?
That is part of the problem, for me - is 33psi for front vs recommended 35psi critical; no not know, but I would assume the extra 2psi for the front tires is because of the weight of the front of the car, and how the psi at that weight would effect the shape of the tire as it attacks snow/slush/ice, during winter driving. (Please note, the above exhausts my personal knowledge on this subject.)
RE. twotone: tires’ size as called for by Toyota, same as stock. Also, have sent email to terrace.com, topic question.
thanks.
2PSI will not make or break anything. The tire pressure changes by more than that as you drive, or from (warm) day to (cool) night.
The two psi difference is largely peanuts. The dealer’s line that 33psi is statistically shown to be best in northwest Pensylvania is likely largely bull.
If all 4 of your winter tires were inflated to 35 psi in a 60 to 70 degree F shop after exposure to 20 degree F they will be 32 to 33 psi or less.
For winter driving you want to keep the pressure on the higher side. Minimum of 35. I like to keep mine over inflated a little (2-3lbs).
Pick either number, not enough difference to worry about. I’d go with 35.
Are you measuring the pressure in the tires or relying on a general statement on the repair order?
“Tires 33 PSI” may have been printed on the invoice for simplicity. The service writer isn’t going to return the vehicle to the tech over a 2 PSI difference, they will just tell you that is good enough.
I know what the placard label pressure is on the cars I service and know which are different front/back but I don’t note the pressure on the work order for this reason. People start asking questions.
During the winter I have to inflate to 38 PSI at shop temperature to achieve 33 PSI outside morning cold temperature. Nobody has time to review this with each customer. Most cars are 8-10 PSI low when they arrive for service, few people care about tire pressure but they seem to care when the pay there bill.
It really depends upon the temperature. I would do exactly what the manual says. You don’t want to upset anyone with another " deflate gate" . Slightly over if you anticipate cold weather. That’s where the Pats were at fault. You don’t want the world PO’d at you for under inflated Prius tires.
I’ve noticed that tire pressure on a cold morning is about 28 to 29 psi and it rises to 32 to 33 psi when the tires are warmed up, right at the GM recommendation. I suppose that I could put a couple of psi extra in, and then I’d be at 34 to 35 psi after 15 minutes on the highway.
What the dealer meant was, “Using 33 psi for all tires means we don’t have to think.”
;-]
jtsanders wrote:
I’ve noticed that tire pressure on a cold morning is about 28 to 29 psi and it rises to 32 to 33 psi when the tires are warmed up, right at the GM recommendation.
Your tires are underinflated. The manufacturer specifies the pressure for the cold morning, not for later after you’ve been driving on them for a while.
A many have said, it’s pretty common practice it seems to inflate tires higher to accommodate swings in air temperature. Even on a cold day before the car has never been used, there is no assurance that the air will not get colder. On a warm day in the winter while driving on the highway, it is entirely possible the tire pressure could rise to the higher thirties. That does not mean you let it out unless you plan on putting it back in that next cold morning. It means for most of us, we ride around with winter tires a little on the " hard" side just to err on the side of caution. It’s minus one this morning as I prepare to leave. Hopefully by inflating the tires to above 35 psi, I have sufficient pressure for this morning’s drive. Air pressure is a variable…and .if you want it at thirty two at zero degrees, it had better be 37 at fifty degrees.
I don’t think handling will change much with 33 or 35 psi. The difference is in tire wear and as the front of the car is heavier, hence the 2 extra psi will balance the wear better front to back. Really, the whole thing is splitting hairs anyway. If you have an accurate digital gauge and your own air pump then you might as well follow the Toyota recommendations on the door jam of the car.
The shop(s) are handing you a line of bull because they don’t want to take the time to top off the front tires to the Toyota spec.