Alright, so I searched the forum to see if there was any information on recommended tire pressure for different tire sizes and different driving situations. I thought it would be nice to create a thread where people could post their specific tire size and what they have the tire pressure set to. I know that the stock tires are recommended to have 32F/30R by Acura, but since I just purchased some 18s, I have 225/40/18 tires. For someone like me who use my car as a daily driver and not for autocrossing, what would people recommend? Keep in mind that the max psi for my tire is at 50 psi.

When you post a recommendation, please include the following:

What tire: (ie. Falken Ziex 512s, etc...)
Tire Size: (ie. 225/40/18, etc...)
Max psi: (ie. 50 psi, etc...)
Front Tire Pressure: (ie. 32 psi, etc...)
Rear Tire Pressure: (ie. 30 psi, etc...)
Setup for: (ie. Autocross, Daily Driving, etc...)

 

Tire: Bridgestone Potenza RE750
Size: 235/40/18
Max. Pressure: 51 psi
Front Pressure: 34 psi
Rear Pressure: 32 psi
Setup for: Daily driving

Had these for about a month now, so they're broken in and running fine. Thought I might need a little more pressure to protect my rims but haven't touched it yet. They came inflated this way from Tirerack - the guy said they'd pre-fill them for my vehicle weight - so I didn't have to add any air right off the bat.

Another good idea for a thread dude.

 

i always thought you were supposed to keep the factory presssure rating no matter what tire you have, except for the spare???

 

Tire: Falken GR-Beta FK-451
Size: 235/35ZR19
Max. Pressure: 50 psi
Front Pressure: 36 psi
Rear Pressure: 36 psi
Setup for: Daily driving

 

Tire: Yokohama AVS ES100
Size: 225/45ZR17
Max. Pressure: 50 psi
Front Pressure: 35 psi
Rear Pressure: 35 psi
Setup for: Daily driving

 

Tire: Kumho Ecsta Supra 712's
Size: 225/40ZR18
Max. Pressure: 50 psi
Front Pressure: 33 psi
Rear Pressure: 36psi
Setup for: Daily and Spirited driving

I like the rears a bit harder/more inflated for better turn-in.

 

Tire: Kumho Ecsta Supra 712's
Size: 225/40ZR18
Max. Pressure: 50 psi
Front Pressure: 35 psi
Rear Pressure: 32psi
Setup for: Daily and some aggressive driving

im not sure if mine number is good .. ~ but i like it so far .. ~
would like to play with the number .. but have no idea how it works ..

 

I've tried on the stock tires
35 and 33
Its pretty darn good, not stiff at all, and inceased a bit in mpg, so i'm happy.

 

Tire:Falken Ziex 512s
Size: 225/40/18
Max. Pressure: 50 psi
Front Pressure: 34/35 psi
Rear Pressure: 32/33 psi
Setup for: Daily driving

I'm going to give this setup a whirl and see how the ride is.

 

What tire: Michelin MXM4 (Stock)
Tire Size: 215/50/17
Max psi: Umm...I forget...
Front Tire Pressure: 32 to 35 psi
Rear Tire Pressure: 30 to 35 psi
Setup for: Recommended tire pressure for daily driving, higher tire pressure for road trips

 

What tire: BFGoodrich g-Force T/A KDW-2
Tire Size: 235/40/18
Max psi: 50 psi
Front Tire Pressure: 34 psi
Rear Tire Pressure: 34 psi
Setup for: Daily Driving

 

Here is a guide to inflation pressures,

The stock recommendation is for the original tire with a particular load rating for that size and weight of car. (homologated for that car)

Going upsize 16 to 17 or 18 inch usually results in a lower load rating on the tire as it among other things contains a smaller volume of air(also depends on sidewall and beltings). If your new tire has lower rating, your inflation pressure should be higher than stock to compensate for the reduced load rating.

Some recent XL (extended or extra load) rated tires can match the original tire load rating and can then use tire pressures equal to the suggested stock pressures.

Of course a modest increase in tire pressures usually gives some gain.

Getting the most from your tires....

This Usually needs some sort of skid pan but most of you can wing it. For a FWD like TSX of course the tyre pressure is higher in front but not always necessarily so. It can also be equal all round except that this usually encourages more understeer. So staggered pressures are used to give the car a better balance. (Some say its because there is less weight behind but you have to ask the question as to why it is so when usually more pressure=better performance and weight carrying capacity)

Balancing comfort, handling and fuel consumption. If you can bear with it usually higher pressures result in better mileage but is detrimental to ride comfort. Handling in a sense is better in terms of sharper more predictable and progressive response. Handling balance is determined by the car's front:rear grip. Most FWD machines understeer and hence a thick front bar is not usually called for. What is necessary is a thicker rear sway bar, within limits.

Mind you for 90% of users an understeering car is probably the best way to keep them out of trouble. For the rest of us searching for a more neutral handling balance is desirable. By compromising the rear grip in a controlled fashion, we can obtain a better handling car. We can use the following to achieve this among others)

Thicker rear sway bar,
Reduced camber
Slight toe out
Stiffer spring rate
Rear ride height
and Lower rear tire pressures!!

However I note many of us have swapped to stiffer springs. This also means there is increased roll stiffness due to the higher spring rate itself(and not the roll bar). ie for a given g-force the car rolls much less meaning to say the difference of height between left and right suspension is much reduced.

If you are still following, then the resultant twist in the roll bar is less, meaning to say that the rear sway bar is less effective. Increasing the rear bar stiffness is necessary with a stiffer suspension to maintain the handling balance. I suspect that although companies like Comptech sell their bars seperately, they are more a match for their own uprated springs.

Adjusting rear tire pressures can be a fast and effective way to reduce understeer, accessible to anyone unlike sway bars, camber settings etc.(but dont go too far)

I digress.....different tires need different tire pressures to gain full performance. for example, the Michelin PS2 is designed NOT to operate with very high tire pressures(another is P-Zero Corsa; 2 bar). The sidewall and tread belt is so well optimised that it is not necessary to pump it up to 35 psi. It likes pressures closer to 30 psi and still manage to deliver good rolling resistance and handling as it has a progressively deformable contact patch and advanced dual tread compound. Most other tires need huge inflation pressures to keep the contact patch stable or to compensate for sidewall flex that they have put in to give comfort. Goodyear GSD3 falls into this category and gives better performance as pressures go up into the mid 30s. However this is not always applicable for every tire. Some tires do not give any more performance as pressures are increased, even giving less as it reduces the contact patch as it baloons out/distorted hence depending on how well they are designed.

All tires gives more performance as pressures are raised from zero to say 30 psi, beyond which performance returns get progressively less and finally reaches a plateau and may even drop in poorly designed tires. Finding this point of diminishing returns is the goal. (different for each brand of tire)

So once beyond the manufacturer's suggested pressures, use your judgement to determine if any more useful performance is gained with higher pressures and how much it compromises ride. It can also cause the suspension to skip in bumpy corners much like a stiff spring or damper rate.

Tire manufacturers rarely give a single recommended pressure because they have no idea as to exactly which car their tire is going to be fitted onto unless it is a homologated tire size for a certain model of car. The best starting point is the car manufacturer's recommendation and work your way up from there till gains are negated by harsh ride and poorer handling. Never exceed the max recommended pressures printed on the sidewall and never go below the stock settings.

Hope some find this info useful.

AL

 

What tire: Yokohama Avid V4S
Tire Size: 215/50/17
Max psi: 50 psi
Front Tire Pressure: 32 psi
Rear Tire Pressure: 30 psi
Setup for: Daily driving that includes a few spirited stints

 

What tire: Michelin MXM4 (Stock)
Tire Size: 215/50/17
Max psi: I think 40 to 45psi
Front Tire Pressure: 35
Rear Tire Pressure: 33
Setup for: Above is for daily driving in mild or warmer temperatures. Longer highway trips (front: 36, rear: 34); cold winter with snow (front: 33, rear: 31)

 

What tire: Stock Michelins
Tire Size: 215/50VR17
Max psi: Not sure
Front Tire Pressure: 35
Rear Tire Pressure: 33
Setup for: Spirited daily driving