Tire Inflation

gliffe · 07-06-2006, 01:06 PM

Hello...
I am relatively new to this forum, and I apologize in advance because my question has probably been covered already. I can't help but notice that quite a few members on this board seem to have tire pressures well above the manufacturers recommended pressures of 35/33. Is this done to obtain higher mpg's at the sacrifice of comfort and premature wear on your tires? I find the ride on my 2006 already harsh when going over bumps. I'd like to get your feelings on this subject. Thanks, Greg.

GreenGene · 07-06-2006, 01:18 PM

When we got the Prius from the dealer, the air pressure was 32/32 - not good. I bumped it up to 39/37 to increase the gas mileage a bit. With the roads around here (especially in the District), I'm reluctant to go any higher. I guess I'm looking for a good compromise between economy and comfort.

aaf709 · 07-06-2006, 01:28 PM

Yeah, it's more for mileage than anything. It's amazing how one low tire can affect it. I keep mine at 42/40 and have had no problems.

**TonyPSchaefer** · 07-06-2006, 01:42 PM

First things first: The front tires should always be two psi higher than the back tires. This is for the weigth of the engine.

Okay, I keep mine at around 43/41 or 42/40.

I had a slow leak in one of my tires resulting from a nail. I took it to Sears Automotive. The first thing the guy did was to check my tires for wear. He went all around and inspected every tire. I got really high marks - except the one with the nail. He said that this was to be expected since it was deflating after all. However, I pointed out, I check my tires every weekend and that tire never got below 36psi which is right about suggested. The others - the ones that showed very little wear - have always been "overinflated."

I like high mileage numbers so I keep them overinflated. Now that I've become a mileage snob, I'll never go back to 35/33. If you prefer comfort, then go with what you like.

rfred · 07-06-2006, 04:04 PM

One thing that I wish I didn't have to mention is to check the tire pressure after you have the car serviced. Our very efficient former Toyota service people took it upon themselves to remove eight pounds of pressure from each of our tires when the car was in for an oil change! And they put 4.0 quarts (roughly 0.5 quart too much, depending on who you talk to...) of oil in the car. And, oh yeah, they wanted to use 10W30. They told us that every Toyota uses it. Our answer, "Well, this isn't every Toyota, is it?"

I would suggest checking the tires once a week when they are cold. I use a pretty inexpensive digital guage and a compressor run off of one of the car's 12 volt outlets.

brandon · 07-06-2006, 04:26 PM

Yeah, I seem to have an ongoing issue with the service shop when it comes to tire pressures. The sticker on the side of the car says 35 psi fronts, 33 psi rears. Whenever I get my oil changed, etc., the car usually returns with 32 psi all around.

I just got back from picking up my Prius after having the SSC 60C work performed. I left a typewritten note with the service people to check the pressures and adjust it to 35/33. I checked the pressures before I even got into the car - 32/31. *sigh* I guess if you want something done right, you gotta do it yourself!

*EDIT* Hey Richard, can you recommend a 12-volt air compressor to me? I'm in the market for one like you describe.

**TonyPSchaefer** · 07-06-2006, 04:39 PM

I have a Craftsman air compressor / tire inflater. It works just perfect for me with a removable digital tire gauge. There's only one gripe I have: it only plugs into the car lighter plug. I can't plug it into the wall. Since I use it 98% of the time to check and top off tire pressure, that's no big deal. However, it came with needles and other adaptions for other uses. I hvae to power up my car to inflate a basketball.

But I do like it: Craftsman Air Pump

jamarimutt · 07-06-2006, 08:48 PM

I use 36/34. Even at this pressure the car rattles like an old car, at 42/40 the suspension or the dash may fall off.

Bill Merchant · 07-06-2006, 08:58 PM

Another point to consider is the tire you are riding on. Complaints of a rough ride or noise may be attributed to the OEM tires. I changed to Goodyear ComforTred tires and 42/40 pressure and like the ride just fine. No excessive tire wear at that pressure, and not harsh riding.

KTPhil · 07-06-2006, 10:44 PM

Glad to hear you like the Comfortreds, Bill. I just put them on, and am also using 42/40. It is at least as smooth as the bald Integrities at 38/36 (probably a combination of the sushioning layer in the tire, and the full new tread). The Integrities wore out on the shoulders, requiring early replacement. I am hoping the higher 42/40 will avoid this with the Comfortreds.

I did notice a return to the twitchiness. Could be the sticky new treads vs baldness, and also the new tires taking a set on the car.

MPG dropped by a good 5mpg (only one tank burned so far), but the new tread and tire set may be the cause, not the tire design. Remember the Integrities are not LRR, either. In a couple of months I'll see if it creeps back up again.

07-06-2006, 01:42 PM	#4
TonyPSchaefer Your Friendly Moderator Join Date: May 2004 Location: Far-North Chicagoland Posts: 10,498 My Car: 2004 Prius Model: Package: #9 Thanks: 39 Thanked 165 Times in 106 Posts Friends: 23	First things first: The front tires should always be two psi higher than the back tires. This is for the weigth of the engine. Okay, I keep mine at around 43/41 or 42/40. I had a slow leak in one of my tires resulting from a nail. I took it to Sears Automotive. The first thing the guy did was to check my tires for wear. He went all around and inspected every tire. I got really high marks - except the one with the nail. He said that this was to be expected since it was deflating after all. However, I pointed out, I check my tires every weekend and that tire never got below 36psi which is right about suggested. The others - the ones that showed very little wear - have always been "overinflated." I like high mileage numbers so I keep them overinflated. Now that I've become a mileage snob, I'll never go back to 35/33. If you prefer comfort, then go with what you like. __________________ Proud father of Priapus: the '04 Tideland BC9 with an OEM EV button and sense of self-righteousness Current Mileage Chicago Prius Group Website Chicago Hybrid Group on FaceBook Find me on faceBook

07-06-2006, 04:04 PM	#5
rfred Senior Member Join Date: Apr 2006 Location: Overland Park, KS Posts: 137 My Car: 2008 Prius Model: Package: #3 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	One thing that I wish I didn't have to mention is to check the tire pressure after you have the car serviced. Our very efficient former Toyota service people took it upon themselves to remove eight pounds of pressure from each of our tires when the car was in for an oil change! And they put 4.0 quarts (roughly 0.5 quart too much, depending on who you talk to...) of oil in the car. And, oh yeah, they wanted to use 10W30. They told us that every Toyota uses it. Our answer, "Well, this isn't every Toyota, is it?" I would suggest checking the tires once a week when they are cold. I use a pretty inexpensive digital guage and a compressor run off of one of the car's 12 volt outlets. __________________ Richard

07-06-2006, 04:26 PM	#6
brandon Senior Member Join Date: Oct 2004 Location: Manhattan, KS Posts: 770 My Car: 2005 Prius Model: Package: #6 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Yeah, I seem to have an ongoing issue with the service shop when it comes to tire pressures. The sticker on the side of the car says 35 psi fronts, 33 psi rears. Whenever I get my oil changed, etc., the car usually returns with 32 psi all around. I just got back from picking up my Prius after having the SSC 60C work performed. I left a typewritten note with the service people to check the pressures and adjust it to 35/33. I checked the pressures before I even got into the car - 32/31. sigh I guess if you want something done right, you gotta do it yourself! EDIT Hey Richard, can you recommend a 12-volt air compressor to me? I'm in the market for one like you describe. __________________ Brandon 2005 Driftwood Pearl Prius, BC (Package #6), Delivered 10/21/2004

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07-06-2006, 01:06 PM	#1
gliffe Join Date: Apr 2006 Location: Skokie, IL. Posts: 18 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Hello... I am relatively new to this forum, and I apologize in advance because my question has probably been covered already. I can't help but notice that quite a few members on this board seem to have tire pressures well above the manufacturers recommended pressures of 35/33. Is this done to obtain higher mpg's at the sacrifice of comfort and premature wear on your tires? I find the ride on my 2006 already harsh when going over bumps. I'd like to get your feelings on this subject. Thanks, Greg.

07-06-2006, 01:18 PM	#2
GreenGene Senior Member Join Date: Mar 2006 Location: Northern Virginia Posts: 175 My Car: 2006 Prius Model: Package: #6 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	When we got the Prius from the dealer, the air pressure was 32/32 - not good. I bumped it up to 39/37 to increase the gas mileage a bit. With the roads around here (especially in the District), I'm reluctant to go any higher. I guess I'm looking for a good compromise between economy and comfort.

07-06-2006, 01:28 PM	#3
aaf709 Ravenpaw of ThunderClan Join Date: Apr 2005 Location: San Diego, CA Posts: 3,839 My Car: 2005 Prius Model: Package: #6 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Yeah, it's more for mileage than anything. It's amazing how one low tire can affect it. I keep mine at 42/40 and have had no problems.

07-06-2006, 04:39 PM	#7
TonyPSchaefer Your Friendly Moderator Join Date: May 2004 Location: Far-North Chicagoland Posts: 10,498 My Car: 2004 Prius Model: Package: #9 Thanks: 39 Thanked 165 Times in 106 Posts Friends: 23	I have a Craftsman air compressor / tire inflater. It works just perfect for me with a removable digital tire gauge. There's only one gripe I have: it only plugs into the car lighter plug. I can't plug it into the wall. Since I use it 98% of the time to check and top off tire pressure, that's no big deal. However, it came with needles and other adaptions for other uses. I hvae to power up my car to inflate a basketball. But I do like it: Craftsman Air Pump

07-06-2006, 08:48 PM	#8
jamarimutt Senior Member Join Date: May 2004 Posts: 986 My Car: Model: Package: Thanks: 0 Thanked 2 Times in 2 Posts Friends: 0	I use 36/34. Even at this pressure the car rattles like an old car, at 42/40 the suspension or the dash may fall off.

07-06-2006, 08:58 PM	#9
Bill Merchant absit invidia Join Date: May 2005 Location: USA \| Oregon \| Portland area \| 97004 \| Posts: 4,100 My Car: 2007 Prius Model: Package: #5 Thanks: 18 Thanked 10 Times in 8 Posts Friends: 60	Another point to consider is the tire you are riding on. Complaints of a rough ride or noise may be attributed to the OEM tires. I changed to Goodyear ComforTred tires and 42/40 pressure and like the ride just fine. No excessive tire wear at that pressure, and not harsh riding.

07-06-2006, 10:44 PM	#10
KTPhil Senior Member Join Date: Jan 2005 Posts: 1,313 My Car: Model: Package: Thanks: 0 Thanked 2 Times in 2 Posts Friends: 0	Glad to hear you like the Comfortreds, Bill. I just put them on, and am also using 42/40. It is at least as smooth as the bald Integrities at 38/36 (probably a combination of the sushioning layer in the tire, and the full new tread). The Integrities wore out on the shoulders, requiring early replacement. I am hoping the higher 42/40 will avoid this with the Comfortreds. I did notice a return to the twitchiness. Could be the sticky new treads vs baldness, and also the new tires taking a set on the car. MPG dropped by a good 5mpg (only one tank burned so far), but the new tread and tire set may be the cause, not the tire design. Remember the Integrities are not LRR, either. In a couple of months I'll see if it creeps back up again.