It should give you a range of psi stamped into the sidewall. I usually try for the middle of the range, so if it states 36~40, I go for 38psi. It's a good place to start, and if you feel its a little "sloppy" while cornering, go up in pressure, if its kinda bouncy and stiff, go lower.
I run 16" Dayton ZR's (exact same tire as the Bridgestone Potenza RE730 Gen 2, but $120.00 cheaper per set!) on my Supra, and think the range is 36~44psi, and have been pretty comfortable with 40psi...
I think mine says the max is 44 psi... and I actually think I have 40 psi now. Its not the driving comfort im concerned about - its the wear, wouldnt want to wear theese expensive tyres the wrong way due to wrong pressure you know..
I think you'll be okay at 40psi. Just my own theory here, as long as you're within the usable range specified on the tire, you probably won't see much difference in wear between those numbers (maybe 500~1000 miles between running one set at 36psi vs. another set at 44psi?). However, if you drop below the lowest usable pressure, you will probably notice a significant amount of wear.
40 psi is too much for just normal driving. I would say 33-35 psi for normal driving. Watch the tire wear as you put some miles on the tires. If you start wearing the center go down a little bit and vice versa if the outside starts to wear more. For reference TRD recommend running 37 psi with 225/45/17s on my Solara. I usually run about 40psi to try and prevent bent rims (not to much luck either ) and they do wear the centers out more.
You should go with ~36 psi. I believe factory recommends 32psi for stock tires (info should be on door jam).
Rule of thumb: You add 2psi for every inch larger in diameter. (Never exceed manufacturers maximum.)
14" = 32psi
15" = 34 psi
16" = 36 psi
17" = 38 psi
You should never run your tire at maximum pressure on a daily basis. In fact we don't recommend it at all. You should leave yourself a margin of safety.
The only reason you should run your tire at higher pressures than recommended is:
1) You race - like Hawaiian
2) You are carrying a load - (I don't think too many of you actually use your car as an SUV... even though I've been known to do that on occasion with my old 85) In this case never exceed GVW.
Heh, I've been known to run 50psi up front at autox... Those poor falkens, I love them, but they are just too.. well... 60series to run low psi.
Lol, on my crap tires out back, I drop them to 30psi for the greatest amount of traction possible. Shit, the back end's going to come out anyways, might as well be a little sooner with some more power to the ground out of the corners.
I'm all about running whatever psi I want (within limits ofcourse) on the streets. I'm going to trash the piss out of them every other weekend anyways. Centers start wearing out? Drop the psi a bit while commuting. Edges take a beating on a tight course? Raise the psi up a bit for the next few weeks. So far my falkens up front have 4k miles (and 3 autox's) and aren't doing too shabby (considering).
I'm sorry but I have to chime in on this, I work in a tire shop and when people come in with their tires set to the max that it says on the tire I just cringe. That is the maximum allowable for the tire and is almost never what is recommended for the vehicle. Look on the glove compartment door and you should find that the suggested pressure for the car is 27lbs front and rear. The rule that Supra GTR suggested is a good one, but only if you don't change the width of the tire. If you are running a 225/50/16 you should probably go up a couple pounds, if you are running something wider, say a 245/45/16 you should keep it just the same. This is because you want the same amount of air in the tire as stock so as not wear out your tires unevenly.
If you want to race get a temperature probe and after a couple laps measure temperatures on each edge and in the middle of each of your tires. If the temps are the same all the way across you are fine, if it is higher in the middle you have to much air, if it's higher on the edges you have to little. This is the most accurate way to get the correct pressure and will also give you the best traction as you are using the entire tire equally. Running higher pressures may feel better because it gives you better response but you probably have less traction at the limit.
I'm curious where you guys are finding lowest useable pressure on a tire, I've seen a hell of a lot of tires in the last three years and I don't recall ever seeing a minimum pressure on any of them. They all have a max pressure but never a min. If you can point this out to me please do as I'm curious but as far as I know the min pressure just depends on the vehicle weight. If you have an old VW bug running at 24 psi is just fine, but if you have a suburban anything less than 35 is nuts. I'm just trying to educate here as I do work with tires for a living. It's true new tires are less sensitive to pressure changes but I always stick with something close to factory because you never know how the car will react.
Sheesh Darin... You make it sound like I don't know what I'm talking about. :lol:
No mean to offend you But I am certified with Toyo. As are most of our tire techs and our entire sales staff. Most of our staff is also Yokohama certified. And since we just brought on Pirelli, we will each be trained on Pirelli Tires.
Running a plus 2 or plus 3 tire at stock pressures is a sure way to bend wheels and destroy sidewalls (aka tire blisters). Keeping tire pressure the same is a common mistake among tire techs. We would never run 32 psi on a civic with 17" tires. I certainly don't run 32psi on my 17s. Not after waiting that long and paying that much.
The 2psi for every inch is not just a suggestion. It's what's strongly recommended by Toyo and several other tire manufacturers. And we've seen the results when this rule is not adhered to by the customer.
Obviously you should never exceed maximum pressures for street use. But then again we will never exceed a plus 6 fitment (20") on a mk2 either. :wink:
And like you Darin, I have seen tire pressures that have exceeded maximum on street cars. In fact one customer came in for a r&b and he had 60 in one tire and 80 in another. :shock: Pulled him aside and set him straight.
People have a mind set other than what you and I pay extra special attention to. I think we as wheel/tire people have taken more tire pressures of our own cars than used a thermometer to check our temps when we're sick. :lol:
But I know we both can agree that by paying close attention to tire pressure you can...
this is basically just a matter of volume inside the tire versus vehicle weight. that formula probably breaks down for ultra-low-profile tires, when sidewall is so little that potholes can bend rims, but a 225/50 is not an outrageously short sidewall.
if you want some uber-performance setup, you'll have to talk to the SCCA guys. But if you just want an all-around safe tire inflation number, I'd say your best bet would be to look for a factory vehicle that shipped with 225/50-16's that weighs about the same as your supra, and see what the factory tire inflation pressure was for that vehicle.
I searched around & got 3040 lbs as a curb weight for an early 80's supra. Current V6 Mustang coupes weigh in at 3066, and the weight distribution is probably even similar. I think this was different in previous years, but starting in 03 it looks like V6 coupes are shipping stock with 225/55-16's. In other words, this is an almost perfect comparison car. Go to a Ford dealer, check the tire inflation guide on a v6 stang, and add 1 or 2 PSI to make up for your slightly shorter sidewall.
SupraGTR, it's nice to see some other tire guys on here. I can see running higher pressures in an attempt to not bend wheels but when people are talking about a 225/50/16 you shouldn't have to worry about bending wheels as that tire still has a pretty good sidewall. I was running 225/45/17s on my Legend at 35psi and never had a problem with bending anything and that was a much heavier car, 3500lbs before stereo. Stock on that car was a 205/60/15 at 32 psi.
To answer Salieri's question I think the stock pressure for the newer mustangs with the 16" wheel is 30 psi front and rear. I know the 245/45/17 needs a higher pressure, 35 psi IIRC.
It's amazing what some tires can hold up to though, I had one customer come in in some older VW cabriolet with stock size on and one tire was at 115 psi, I kid you not, I had to go get my digital tire guage to even check it as it read off the scale on all the shop guages. The tire sounded like a basketball when you bounced it, ping! I lowered it back down to the stock 28 psi and talked to the customer. Her other tires were only at about 60psi. :roll: She was complaining of a harsh and bouncy ride, go figure.
I checked the TSRM for my '82, and it recommends 26 psi for the 225/60/14's, and that is what I usually run (when they don't go flat cause they are so bald). Based on James little rule of thumb, I should run 30 psi on my 245/45/16's :?:
I have 225/50-16s up front and 245/45-16s in the back. The driver's front tire looked low, so I took the car to Firestone to get the pressures checked and see if they'd air it up. The tech checked it and said it was at 27psi and that stock is 26. Then he let air out of all my other tires so now they're all at 26 psi too.
Needless to say, the front is now quite low and so I searched and found this thread. Should I refill them to 32/30 or what? They're Fuzion ZRi's and have a max rating of 51 psi.
I figured that. I think I'll run 32 front, 34 rear as suggested by James R.
I told the tire dude that the aftermarket rims probably needed different pressures, but he assured me that the stock number was fine and that you can't tell if a tire is inflated to the right pressure just by looking at it. He's the same guy who told me he used to have a Celica hatch like it and that he and his wife "got busy" lots of times in the back cuz you can fold the seats down. He was a winner and I don't think I'll return to his store.