tzakiel

Welp, I just decided to bump my PSI up 2.5 in the front and 4 in the rear... and all I can say is holy cow. I'm going to take a lot more consideration of tires and PSI from now on. The car feels lighter, turns easier, and accelerates better, all in a "very noticable" way.

Pure Adrenaline

iTrader: (2)

NFLblitze1

did u add the PSI in ur tires...because they were low on air? or did u add 2.5 psi and 4 psi to the stock specs

blktl1

100% correct. you car will be more of a stiffer balance ride with more air and more of a mushy ride with less. I always chekc my pressure every 3 days to make sure its where I want it.

tzakiel

No, I am running a PSI that i can only guess is close, since i have aftermarket rims and tires. I'm at 41 front 43 rear right now and it seems good. 245/45/18 toyo proxes 4 and 18x8.5 wheels.

Ron A

Nobody should ever run tires for street use at 41 and 43 lbs. If you set them when they were cold, the pressure will increase, depending on the outside temperature and the speed you are driving, at least 3 lb, which makes it even more worse (bad English but I'm making a point here).

What does it say on the sidewall about maximum tire pressure?

Not that it matters for this conversation, because that is way too much air, but I am just wondering.

ARX-01b

iTrader: (1)

Only problem is you've dialed more understeer into the car. Not a great trait since the TL fights understeer from the factory. You'd be better off with 43 in the front and 39-40 in the rear.

You might pay attention the the wear patterns and if the center of the tire shows more wear than the sides, you might need to drop the air pressure a couple of pounds.

whatwasthat

hmm.. ths is making me think...

how much do would i have to put? outside is just at the freezing point (32 deg.) and i have tsx rims w/ falken 512.... i put them at 35 psi (i checked this last week when it was about 55-60 degs)... should i stay? or add more to compensate for the colder temperature..?

ARX-01b

iTrader: (1)

When the temp drops so does the air pressure of your tires. Probably not a big deal right now as the temps continue to yo yo. Once the temp remains more constant, check your tires first thing in the morning and add air accordingly.

If you look in the driver's door jam it recommends what you need to be running for 17"s

tzakiel

Ron, when I got my tires and new rims installed, it rolled out of the shop at 41 front and 45 rear. So I'm not sure why you say that? I am running at less than the initial fill.

the max pressure for the toyo proxes 4 245/45/18 is 50 lbs. I have not been able to have anyone tell me what the correct pressure is for my car, including my dealer, ronjon (i have ronjon rims), the tire shop (they said they filled it correctly the first time but dont have a record of what that was) or this forum.

whatwasthat

well, my door jam will say it for the stock 16" wheels i had. i changed to TSX rims. what is the correct pressure for 17" TSX rims?

tzakiel

sorry i meant 245/40/18 in my post just above

whatwasthat: stock 3rd gen rims are 17"

sparky57

I'm with Hondafans concerning reducing understeer, not increasing it. I run 245/40-18s as well and use the factory A-Spec settings of 39/36 front/rear.

With those higher pressures, you would need to stiffen the suspension to optimize such a setting. It's all about tuning, not maximizing one parameter alone.

rw

Adobeman

Since "sidewall chalking" is no longer recommended for modern tires I guess you'll just have to get a pyrometer and measure the temps.

Seriously, aren't the a-spec rims 18" ? If so what are they all running ?

tzakiel

I made a mistake in my reporting of my PSI, somehow they must have alreayd been hot even though i had only gone 1.5 miles.

The real PSI I am at that feels good is 38 front, 40 rear. And that seems really sweet. Like I said when they came out of the tire shop they were at 40f and 45r which I thought was bizzare.

Also I do have the comptech RSB so that helps handling in general too.

tzakiel

But you have the MT or the AT? The specs are different for PSI.

sparky57

Well you have successfully negated the benefits of your $110 purchase using a 5 lb differential in the wrong direction.

rw

sparky57

I have the manual. While the suspension stiffness is slightly different between the two, the overall assumption is that those who choose the manual want better cornering.

Twenty five years ago, however, I biased the front tires of my '81 Accord for the same reason. There is a current Pontiac that achieves the same result by putting larger tires on the front than the rear.

rw

tzakiel

I heard back from Toyo. Using the information I gave them about size and model of the car, they tell me the correct PSI is at least 39 PSI all the way around. So that's what I'll be using.

Pure Adrenaline

iTrader: (2)

Grand Prix GTX and the Bonneville GXP come with wider front tires.




As for the tire shop... do you honestly believe they know what they are doing? They just fill it up to whatever pressure they "think" is okay and that's that. I've never once gotten the correct tire pressure at a tire shop. Only the tire company knows it best, and this information is pretty easy to find. Any major tire manufacturer has web sites with the specs of their tires listed with the range of proper air pressure, and you can choose whatever pressure you want from there.

mbwmn

wow, dude we're OLD.
sidewall chalking....

Pure Adrenaline

iTrader: (2)

I've heard of this sidewall chalking....

Actually, I think the Spec Miata guys still use this method, don't they? I was reading an article on the Spec Miata Racing not too long ago and I believe they mentioned it.

sparky57

Was that question directed to me?

I go for the manufacturer's recommendations since they tuned the suspension for a given setting. The tire manufacturer has no idea whether the tire is going to be used on a FWD, RWD, or mid engined car where the ideal front to rear pressures are all different.

rw

Pure Adrenaline

iTrader: (2)

No, that was directed to tzakiel.

You're right, though. Tire manufacturers don't know the application of the tires. However, they do know the range of pressure that the tire should be inflated to. hence the reason I said, once you find that info from the manufacturer, find the pressure you want to inflate it to within that range.

Tire shops generally don't know the recommended pressure, much less the owner's preference. So they just pump 'em up and send 'em out. That was my point. For instance, my T1-S were pumped to over 44 psi in all 4 of them when I had them mounted at Belle Tire, and that is pretty high for 235/40/18 on a 2G TL. I currently run them at 38F/35R and that's a bit on the stiff side with soft damping rates on the street. I tend to mess around a lot with my damping rates and tire pressure.

tzakiel

dunno if you guys saw, but i talked with Toyo and they looked up my car specifically and the correct pressure is 39psi all around.