dbqtown

Here is a link to a sight explaining how a front drive car should be set up to obtain a neutral balance.


http://www.turnfast.com/tech_handlin...ling_pressure5


If anyone has any other input from experiance of different pressures please comment.

Will Y.

The Tire Rack website also has some general suggestions: http://www.tirerack.com/tires/tirete....jsp?techid=58

princelybug

iTrader: (16)

Good info.

BigJack75

So what should we set the tp too for regular street driving? The article mentions driving the car on a track which I will probably never do.

corduroy

So 34/35 PSI is ideal?

imj0257

iTrader: (1)

Hmm interesting. I usually set mine at like 32-34 all the way around.

The last thing I want to do is accidentally overinflate a tire and have the whole damn thing explode in my face like what happened to that one dude at that one place that one time.

Will Y.

There is a plate on the driver's door or frame with the recommended tire pressure, which is also stated in the owner's manual, for your vehicle as it came from the dealer.
However, the recommended pressure is a base-line. You can experiment to find a pressure you like.
Keep the cold pressure below 40 psi for street driving and you'll be fine.
Depends what you want to do and your ride/handling preferences.
The recommended pressures vary somewhat by year, transmission type and OEM wheel size.
The pressures I use on my stock 17" wheels are 38F/35R, although 32F/32F is recommended on my door plate.
That is unlikely to happen if you keep the pressures below 40 psi (cold).

TL|GTX

tirerack and that other website say the oppostie things, tirerack is retarted, u dont put more psi in a front wheel drive car, to reduce understeer. Settings should be 28cold front, 34cold rear.

I hate cars

Generally you're going to have more pressure in the front tires of a street driven FWD car to get a flat contact patch with 65% of the weight on the front tires.

There are so many variables you can't recommend one pressure for all FWD vehicles and tire combinations.

The pressures on the door placard mean nothing once you replace the factory tires. My current tires have a max of 50psi cold but I run them around 42F and 40R.

Usually the fronts and rears warm up about the same amount in street driving but an understeering FWD car at the track will raise temps in the front tires much more than the rears.

Personally I would rather adjust the swaybars than reduce traction from the tires by under/over inflating one end.

nfnsquared

Who's retarted?

nfnsquared

Not according to the 2004 owner's manual. 35/32 for MT, 32/32 for AT, regardless of tire brand or type (summer/all season/snow), assuming of course you stick with the recommended size (235/45/17, 93W). pp. 222-224

I hate cars

It may by chance work for both all season and summer tires that came on the TL but it's invalid once you go aftermarket. Load ratings change, sidewall construction changes, many, many other factors determine the correct pressure. I went out and looked at my current tires and I was wrong on the pressures. 55psi is the max cold pressure. If I only ran them at 35/32 they would not have the load handling of the stock tires but at 55psi they will handle more load. They would also build much more unnecessary heat if I ran them at the stock inflation pressures.

nfnsquared

You're missing the point. The Acura recommended tire pressure stays the same for the OEM tire size/load rating regardless of tire brand.

You're not running the OEM tire size nor load rating. In fact, those size Nittos are extra load tires (98W), so OEM recommendations won't apply.

For anyone else running the OEM tire size/load rating, the OEM tire pressure recommendations are valid, regardless of tire brand.

I hate cars

I'll give you that the OEM recommendations are closer with a tire of the same size and load rating. However they're a very rough estimate once you go aftermarket. I would pay more attention to the max cold pressure on the sidewall than the door panel. I've had tires of the same load rating as stock that had 50psi as the max. Are you saying you would run 32psi in a tire rated for 50psi? I hope not.

nfnsquared

Yes, if OEM size/load rating, stick with owner's manual recommended tire pressure:

Tirerack.com on Max inflation

"A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. However the tire's maximum inflation pressure should only be used when called for on the vehicle's tire placard or in the vehicle's owners manual. It is also important to remember that the vehicle's recommended tire inflation pressure is always to be measured and set when the tire is "cold". Cold conditions are defined as early in the morning before the day's ambient temperature, sun's radiant heat or the heat generated while driving have caused the tire pressure to temporarily increase."

http://www.nhtsa.dot.gov/cars/rules/TireSafety/ridesonit/brochure.html

"Understanding Tire Pressure and Load Limits

Tire inflation pressure is the level of air in the tire that provides it with load-carrying capacity and affects the overall performance of the vehicle. The tire inflation pressure is a number that indicates the amount of air pressure– measured in pounds per square inch (psi)–a tire requires to be properly inflated. (You will also find this number on the vehicle information placard expressed in kilopascals (kPa), which is the metric measure used internationally.)

Manufacturers of passenger vehicles and light trucks determine this number based on the vehicle's design load limit, that is, the greatest amount of weight a vehicle can safely carry and the vehicle's tire size.The proper tire pressure for your vehicle is referred to as the "recommended cold inflation pressure." (As you will read below, it is difficult to obtain the recommended tire pressure if your tires are not cold.)

Because tires are designed to be used on more than one type of vehicle, tire manufacturers list the "maximum permissible inflation pressure" on the tire sidewall. This number is the greatest amount of air pressure that should ever be put in the tire under normal driving conditions. "

I hate cars

We're sort of agreeing here.

Of course the number on the sidewall is the max cold pressure. But it still gives an indication of the pressure required to get a flat footprint and run cool. A tire with a higher psi rating will require a higher psi to run right with all else being equal.

You've got to think about the engineers' intentions when recommending tire inflation pressures. I'll guarantee ride comfort takes priority over performance. Most owner's manuals have a normal pressure and then a higher pressure for sustained high speeds.

In the real world I've had to adjust tire pressures many times away from the pressures listed on the door decal to get the proper footprint. Those websites are a basic start but they don't hold true all the time or even most of the time. There are more factors in aftermarket tires than just load ratings and sizes. You can have two tires with the same ratings and size that require different pressures and have completely different internal construction.

So in other words, use the factory recommended pressures as a starting point but you will likely have to adjust to find the optimal pressures.

nfnsquared

As far as Max Inflation Pressure, my understanding is the same as noted in the Tirerack.com article:

Namely that Max Inflation Pressure is the absolute pressure (cold) that the tire should be inflated to under any circumstance. I've found zero documentation indicating that it is the pressure that gives maximum footprint. In fact, there are several sources that indicate over inflation (beyond the placard tire pressures but still below or at max inflation pressure) could lead to uneven wear (crowning) of the center of the tire.

Part of the auto maker's testing to determine placard PSI includes tire wear, temperature, handling and footprint factors. It is doubtful that any car/tire combination will have a single PSI that optimizes all of the above factors. Hence, placard PSI is a "best fit" PSI.

Everything I've read indicates that you should use OEM PSI's when using tires that meet OEM specs. [Again, noting that Acura recommends higher tire pressure (39PSI) for sustained speeds above 118MPH]

Your statement that tires requiring a higher max inflation pressure will require a higher "operating" or "placard" PSI (my words) is generally true. Generally, tires with a higher max inflation pressure have a higher load factor and vice versa. On these tires, generally speaking, the placarded recommended PSI would assumed to be higher (assuming that the auto manufacturer tested optimum inflation pressures for that tire's size and load factor).

Once tire specs deviate from the auto maker's OEM specs, you're kind of in uncharted territory (note I didn't say dangerous or unsafe). If running a higher load factor tire than OEM specs, one would assume that a higher operating psi could safely (and maybe should) be used, but again, no one has tested an optimum PSI for that combination.

And finally, I would never run any tire at max inflation PSI, regardless of vehicle or tire. (Again, all of the above assumes normal civilian driving conditions).

smarty666

on the base TL cold, I keep my fronts at 34psi and my rear's at 33psi; anything more than this and the rides gets terribly choppy, at least too much for my taste!

DWL TL 06

[quote=Will Y.;11684504]
The pressures I use on my stock 17" wheels are 38F/35R, although 32F/32F is recommended on my door plate.

this is what i run also. in a FWD car, to reduce understeer run 3-5 psi higher in the front tires.

DWL TL 06

[quote=Will Y.;11684504]
The pressures I use on my stock 17" wheels are 38F/35R, although 32F/32F is recommended on my door plate.

this is what i run also. in a FWD car, to reduce understeer run 3-5 psi higher in the front tires.

DWL TL 06

^^^ i forgot to mention that ^^^is for normal street/freeway driving. if you track your car, you need to take tire temps and air pressures for all 4 tires and make adjustsments

I hate cars

[quote=DWL TL 06;11688403]This is a common assumption and it's usually wrong. This assumes the fronts are being run 3-5psi low already.

There is no magical number as many like to pretend around here. Like I said, maximize tire grip first with the proper pressure and then tune the balance using the swaybars.

dbqtown

I posted this for people who like to drive a little more aggressively on back roads. The purpose is to have your fwd car handle more like a rwd car. Ie... when you enter a corner at speed the back end has
a tendency to kick out because the psi difference causes the front to have more grip than the rear.

dbqtown

I posted this for people who like to drive a little more aggressively on back roads. The purpose is to have your fwd car handle more like a rwd car. Ie... when you enter a corner at speed the back end has
a tendency to kick out because the psi difference causes the front to have more grip than the rear.

I hate cars

The thing is, most RWD cars also understeer from the factory. In fact pretty much every car understeers from the factory.

You can go into throttle induced oversteer with RWD but steady state they do the same thing the TL does.

The TL will kick the tail out in stock from from lifting throttle in a hard corner in most cases.

The ultra popular Progress RSB will give you all the tail out action you could ever want.

NAiL05

If I go on long road trips I run 40psi all my tires. Local I keep it around 35. Usually when I am out on a curvy road I am around 35-37 front with 40 in the rear.

I hate cars

Just read the article and I agree with it.

It mentions balance, swaybars, and how they affect tire temps. Just remember, for daily driving all 4 heat up and pressure rises about the same. You're not going to see significant differences until you're pushing the limits so don't go to the extreme like 8psi more in the rear.

TSX-S2000

My $0.02:

Factory recommended tire pressures are typically for a compromise between handling and ride quality. Not every driver is an enthusiast looking to obtain every possible performance enhancement from their car. Cars are marketed for the masses.

Also, tire pressures should be optimized for the load they are carrying and the speeds they will be operated at. Obviously your car will ride and handle differently with 4-5 people in it. An underinflated tire will also generate more heat (and is more likely to blow) than an overinflated tire (unless the tire is grossly overinflated to begin with).

Different tire brands and models have different ride and handling characteristics. Tire pressures that you found working well with one make/model of tire may not work well with a different make/model. Sidewall sitffness varies. Adjust accordingly.

FWD cars carry more mass over their front wheels (usually 60-65%). With a stock FWD car being setup to understeer from the factory (which is the safest handling trait for unexperienced drivers -- again, the majority), the extra weight over the front wheels only accents the understeer more.

From my experience, if you are trying to make the car's (FWD) handling more neutral, and make the ride quality similar front-to-rear, increasing the front tire pressures over the rear helps. This sharpens the steering response, reduces sidewall flex (the tires don't roll under as much in extreme cornering), and stiffens the ride quality in the front to counter the additional weight sitting over the front end.

I personally run my tires (Bridgestone Potenza RE760 Sports) at 36F/33R and under normal driving conditions, that 3 psi difference is maintained at temp (where they settle to 40F/37R according to the TPMS).