JDMxB

Ok, I've gotten a mixed bag in search of the answer to my question, so I figured I'd finally post.

How do I determine the right tire pressure, if I go to bigger wheels--like right now I'm on 18 inch Toyo Proxes FZ4.

Some people say use the recommended on the sticker for the car.

Some people say use the max psi listed on the tire itselt

Some people say use -2 from the stock psi recommendation.

I don't want to be balloning my tires, but I don't want to risk getting anything bent either.

So, to you guys with 18's or just anything bigger than stock--what and how did you settle upon the right psi for your tires?

nacy333

Isn't there a recommended tire pressure on the tire itself? Not the max pressure but the recommended. I would think that should be the proper pressure regardless of what rim you are using (unless you are stretching out the tire or have to wide of a tire on the the rim.

JDMxB

So out of all of you guys, noone else can help me but my boy nacy?

CMON PEOPLE...I KNOW AT LEAST 4-5 PEOPLE THAT HAVE 18s...

scionRixB

I have 19s, called my dealership to and they had no clue, even though I got the car with the set on already and had no choice of buying them wthout since it was the last in the lot. I called Spy Eng., and the nice person I spoke to said a resounding 35lbs. for my 19s. I dont know if that goes the same for the 18s.

nacy333

How about looking it up on the Site? Just figure out what tires that you've got, go to Tirerack.com or the manufacturers website and look up the specs for tire pressure. You should by all means go with the tire pressure recommended by the manufacturer.

noics

i have a 68 dodge that has 215/45/17 front and 235/45/17 back tires and the guy from americas tire co said to keep both sizes at 35 pounds

yanges

hey there

the tire guy who did my tires and rims said to keep them about 34psi for best ride.... i have 215/40/17's....

and that is while the recommended is 50psi...of course you can go higher with a much stiffer ride, and lower but tread wear will suffer....

so 34-35 should be good i would think..... i tried 36 in mine and it felt a little rough....

And last but not least, you gotta get one of these:

http://www.smartcarproducts.com/products_page.html

you set the gauge to the pressure you want and it cuts off at exactly the right pressure.....every tire is the same.....

i got one and it works fantastic!

avus

on our range rover, the recommended tire pressure for the front is 28, while the rears are 34 - both tires are 255x55 18s.
the general thinking i go by is use the recommended car manufacturers tire pressure guidelines as a reference and extrapolate to your tire size.

JDMxB

Hey Nacy--it's not exactly as easy as "looking it up on the site"--otherwise I would have done that without asking all of you guys for your opinions.

I called my local discount tires, and he told me that with the stock tire size, and the way that the 215/35/18s are plus sized--I should be running 35 lbs each.

As you can see--not all vehicles have the same tire psi recommendation. For example, that range rover guy.

And no, there is no recommended tire PSI printed on the tire, only the MAX psi...they can't recommend a UNIVERSAL PSI on a tire--because every car is of different weight...a scion doesn't weigh as much as an escalade--hence the need for the different PSI depending on stock, and vehicle load.

Thanks for everyone who helped. I appreciate it.

yanges

here is an excellent tire comparison calculator:

http://www.saturnperformance.com/tech/tiresize/

put in stock size of xB for example, 185/60/15 and then put in tire size desired and see the difference in size and effects on odometer....

my 215/40/17 tires are only .1" or .8mm bigger than stock, which is minimal and has little effect on the odometer reading as larger size tires do.....

scionaraxb

I emailed the manufacturer of my 215-40-17 tires about the recommended tire pressure
Here is the reply I got.....

"The inflation pressure for larger aftermarket tire and wheel combinations is always what's listed in the owners manual of the car for the smaller original equipment tires. Automobile manufacturers determine the recommended tire pressures for your car, and those values don't change when switching to larger tires. The air pressure inside of the tire is what supports the load of a car, not the tire itself."

Hope this helps.

LVXB

THAT DOES HELP! check it out i did a search and hit a post that NAILS my question exactly. From five months (or 4 years in scionlife time) ago. Not to shabby.

Oh and for anyone who cares reccomended tire pressure as printed on the inside of the drivers side door is 29 psi

squirrel

I'm running 40 psi on 205/40-17s. The max pressure on the tire is 44 psi.

HTH,

CBSIMONSEZ

Here is my take on the tire issue, having sold some tires in my day, i have tried this method and it works pretty good.

Rule of thumb, most tires need anywhere from 32-35 PSI for every day driving. If your racing, you can deflate them to as little as 20PSI for added traction. So, keeping in mind your shooting for somewhere between 32-35 PSI, try 35PSI first, see how you like the ride. If its a little rough, reduce it by a pound at each tire, but i wouldnt go below 32PSI, then your just running on an under inflated tire, which will wear your outside edges out, while leaving the center tread intact. Also, keep in mind that your car is front end heavy. This said, you may want to keep your rear tires a little less in the pressure dept. With all the weight in the front end of my NEON, i have 34PSI in the front, and 32PSI in the rear, giving the car an over all great ride. If your not going to have anything heavy in the rear, consider running 32PSI at the back, and maybe 34PSI in the front; also taking into consideration what your road conditions are, if its rough, you may need to run more pressure to save the lip on those rims.

BTW .... MAX are pressure should only be used if you are towing, or if the car is pushing the max weight limit. Otherwise, your ride will make your teeth hurt, and you will wear out the center of the tire ( over inflation ) while leaving the outside edges still intact. Hope this helps.

scionaraxb

Did you READ my post? here it is...........Read the first line again............note the "Quote" from the tire MANUFACTURER.....

I emailed the manufacturer of my 215-40-17 tires about the recommended tire pressure
Here is the reply I got.....

"The inflation pressure for larger aftermarket tire and wheel combinations is always what's listed in the owners manual of the car for the smaller original equipment tires. Automobile manufacturers determine the recommended tire pressures for your car, and those values don't change when switching to larger tires. The air pressure inside of the tire is what supports the load of a car, not the tire itself."


I didn't think the "old school 32 psi "would apply to our small cars. That came from the days when all cars were 4000 lbs or more.......times have changed and so should our way of thinking.

yanges

29psi is definitely too low....

the guy that installed my wheels/tires personally drives vehicles w/ various psi to determine the best setting for ride quality...

i have 215/40/17's [Yokohama's] and his take is that 33-34psi is best for ride quality and tread wear.....he said any lower pressure would result in poor tread wear over time....but if you want a firmer ride, add a few lbs....

that is my 2 cents....

JDMxB

EXACTLY why my frustration was vented with the original post, back in 1982 up there.

There is no way in hell that 29psi is the "right" pressure for an 18 inch tire...just try it one day, and maybe if you like your rims touching pavement squashing tire, then it will suit you just dandy.

I ended up calling my wheel guy--and he recommended 35 psi for 215/35/18 with an original psi of 29. Take it with a grain of salt--but that's what I'm running.

fr130

Didn't want to start another topic:
Not sure why but the stock tires pressure was close to 40PSI on all four :twisted: Someone forgot to lower the PSI

I knew I should have check the pressure once I got the Box. Oh well, the OEM Goodyears are not that good anyway. The ride does feel different. Not sure if it's a goodthing or not. It's just different.

sithscripter

A lot of us had the same experience. There was a thread on the subject a while back -- a dealership employee explained that the tires are overinflated for shipment and neglectful / forgetful / improperly supervised porters don't deflate them to the proper pressure.

A seemingly small thing but it could have caused an accident ...

CBSIMONSEZ

You do know that you cant take a PSI reading while the tire is hot, right? You have to check you PSI while the tire has cooled off from driving more then a couple of miles.