BimmFiniti

When I bought my 996 a year ago, I set the tires up per the manual for 18" wheels: 36 psi front; 44 psi rear. The car came with 235/40ZR18, 285/30ZR18 Toyo Proxes T1R, siped (not my 1st choice, but supposedly still a good tire). Right away, I noticed that the ride was way too harsh @ 36/44 and have since dialed the fronts down to ~30 and the rears down to ~36.

I just got back from a very fun, but quite frankly bone-jarring & noisy 400 mile roundtrip in the car with the tires @ 30/36. The tires had a huge variation in ride comfort and noise level on the trip and, at one point when I pushed the car past the century mark, the front tires exhibited some concerning "hopping" (other runs to similar speeds were fine, so I think this one time was the tires reacting to the road surface).

My questions:
* Is this level of harshness and extreme road noise normal?
* What do you guys run your tires at?
* Do I need to go down even lower in pressure?
* Does anyone have any thoughts about the Proxes T1R? I'm a Pilot Sport PS2 guy myself (have them on my 330i & swear by them), but I'm curious if I'd see similar extreme harshness, noise and surface reaction from from them as well?

I'm used to a sport-biased ride (my 330i has the Sport Package), but this seems out of whack...

Fissionx

How old are the tires? They should have a manufacturer date on them a four digit number stamped on the side wall to show the date XXYY where XX is the week number and YY is the year number ie 2207 is the 22nd week of 2007. As tires are heat cycled they get harder, lose grip and make more noise; this is life. The TR1s which came on my car sucked and I replaced them with PS2s. The PS2 will be much more quite, smoother and have gobs more grip than the TR1s.
It sounds like your wheel may be out of balance if it is, 'hopping'. I run 37 front 42 rear psi HOT. I would suggest you run the same or factory.

BimmFiniti

I can't find a date code on the tires (at least in XXYY format), but I know they were purchased in December of '06 from Les Schwab because I have the receipt from the previous owner. Assuming they weren't sitting on the shelf for a few years, they're not that old.

I wonderered if the wheels were out of balance, too. I think I need to get them looked at.

Interesting points comparing the T1R to the PS2. That's what I'm looking for. The grip on the T1Rs seems OK right now (although I haven't tracked the car to really see), but I am really disappointed with the ride, even with pressures lowered.

JDSStudios

It is dangerous to underinflate so much below the recommended pressure:
1. Weakening of side walls
2. Excessive heat
3. Deformation

If you hit a pot hole with underinflated tires, you could also bend your rims and rupture the tires.

If you want a softer ride, consider different shocks and springs... or get a mini-van?

PS: if your Highway 400 ride was at around 1:40 AM or so, I was following you between
langstaff and 401 (you went East, and I went West)

PS2; your plate last 3 numbers are 928?

C4CRNA

How to tell the age of a tire

http://www.tirerack.com/tires/tirete....jsp?techid=11

AndyK

Get new tires! When I first got my car, it had worn Conti summer tires, and the ride was harsh, and the car lurched around at every bump in the road. I put on nice new Potenza Pole Positions, and the car rides beautifully now!

It IS a 911, so you will hear road noise from the huge tire footprint, but the ride shouldn't be harsh like that.

sjfehr

Underinflating like that is just inviting tire and wheel damage, and is probably hurting mileage as well. One thing you're probably not seeing is rollover; when you corner with your car, the lateral forces want to take the tire and roll it under your wheel. Normally, the pressure and sidewalls resist this force, but when the tire is underinflated, the sidewall will roll under the car and will roll on the sidewall. (In addition to all the not-so-great-things this does to your wheel and tire, you also lose grip and can have an accident.) When racing on street tires, people will even add additional pressure!

You have a sports car. Sure, it's got a lot of luxury attributes as well, but it's still a sports car. This is one of them. Properly inflate your tires and learn to love the response

Bear in mind this may only be written on one side of the tire, so you may have to jack it up to get around to the backside to read it on all 4 wheels.

OCNYPORSCHE

Try keeping the rears at the recommended tire pressure. Then dial the fronts down to about 2 less than recommended. I found this to work well. Remember that we have a rear engine vehicle, so it is hard to compare to BMWs. I had the same problem when I first got my 996.

wross996tt

Just curious...is this your first Porsche?

C4CRNA

Did you post pitcures ??

sbpsu354

I have those Toyo tires on my BMW 530i and they are very loud. When I bought my C2 in June last year I installed 2 new Pilot Sport Ribs on the front and was amazed at the drop in road noise.

BimmFiniti

Thanks for all the comments, guys. Well, at least most of them


I'm gonna bring 'em back to Les Schwab and have them check the balance, first.

I'll try to find out, but I suspect they're not that old.

Great feedback. I am wondering about the comparison between the Toyos and PS2s. I maybe have been spoiled with my PS2 experiences??

I knew I was gonna get some flack on these comments! I love the sports car ride and feel, don't get me wrong, but I think something's not quite right.

No, that wasn't me. I'm in Washington state.

I have a while ago, but I repost. Always like to show it off.

BimmFiniti

As requested, here's some pics:



Attachment 351558


It's a 2002 base 996 with the following equipment / options:

• Seal Grey Metallic
• Black Full Leather
• Advanced Technic Package
• Power Seat Package
• 18" Lt Alloy Carrera Wheel
• Wheel Caps with Colored Crest
• Porsche Stability Management
• Supple Leather front and rear
• 3 Spoke Str Whl - Carbon/Leather
• Porsche Crest in Headrest
• Flared Rocker Panels
• Brake / Shifter Carbon Aluminum
• Rear wing (don't have the official name for this one)

Jon996

Wow, nice! FYI; I run a little lower in pressure than Porsche recommends. From talking to the dealer and even PCA, it is not that uncommon. For me I am running 32F and 40R.

BimmFiniti

Thanks! I think she's gorgeous, but I'm obviously biased! The car was basically brand new when I bought it, too, with only 15K miles. I have 19K on it right now.

Thanks for the pressure info. i need to find a happy medium. Think I'll try close to what you're running.