I have 17" Boxter rims and now run Bridgestone Potenza RE001's 205/50 on the front and 255/40 rears.

My previous tyres were Goodyear F1's, those i ran at 36 psi all round and near the end of their 30,000km's showed signs of being slightly over inflated.

But my trusted tyre guru has recommended that i run the Bridgestones at 42 psi front and 46 rear! Has he turned senile?

TIA

 

G'day Nick,

Those figures seem very high even for the R001's. I've heard of guys running 40 psi on the rears but having their false teeth chattering away from the harsh ride... I would be looking at starting around 34 front and 36 rear and see how that feels and then work up or down. I'd be pretty surprised if anyone here was running the sort of tyre pressures your guy recommended.

Neil

 

I thought 17" were suppose to be 36# all around on our cars.

 

This is the recommended tire pressure for 17" on a 964.


Probably!
I wonder how he came up with those figures?

 

I have been busy with re-calculating tyre-pressure since 2007. Made several Excell-spreadsheets for it
All with use of the formula the European car manufacturers also use to determine the advice pressures.
Search for all the items that are asked in the next form and make your own advice ( for your own risk, I have to write)
http://cid-a526e0eee092e6dc.skydrive...0tyre-pressure
in this map always take the newest spreadsheet, and there are examples.
If something isn"t clear or you want to know more, ask here.

But the advice the manual gives is for the original tires and is so put down, that you can never blame the car-manufacturer for to low pressures. But if you know what you are doing, you can go much lower for some conditions.
If you know the exact load on each seperate wheel , then you can savely calculate the pressure needed.
Always take some extra ( 5% to 10% ) for savety ( loss of air in time, incorrect readings of weight and pressure). But People dont know that exact, so if you keep to those ridiculas high pressures they advice you will never have to low pressures. Your dentist will be verry happy with you then. That is why they dont give advices for normal use anymore , as they did before 2004 .... I estimate.
I think it has much to do with the roll-over accidents by tire-blewout that happened around 2000 with the Ford Explorer with firestone tires in America. more then 100 people died by that.
Firestone blamed Ford of using to low pressures, but lost.
Fact is that the American TRA uses diferent formule then the ETRTO (Europe).
TRA comes to lower pressures.

 

I have been running the 17" Boxster wheels with Goodyear Eagle F1s at 36psi all round. I run them 40 psi hot at the track and the wear seems even. If the pressure goes over 40 on the track they start to squeal a lot. They are almost worn out after 3 years at 10k km with lots of track use.

 

Respectfully, I do not agree with jadatis. The recommended pressure from for 17's is 36 in front and rear. The best source for confirmed response is from a certified Porsche mechanic. I have spoken with two and both agree that the Porsche recommendation is the correct.

 

OK, just for clarification, when you talk about tire pressure, is that cold or hot, as in after a good 10 mile run. I have done a bit of experimenting myself, and I found 32 front, 33 rear cold pressure work the best for me, that equates to about 35/36 hot; the tires are Yoko AVS ES 100, probably the noisiest tires you an put on your car, soon to be replaced.

 

I run:

36/36 cold for everyday road use, and
31/32 cold for track use (this translates to 36/36 hot at the track).

 

I normally use 36f/38R for road use, and it goes fine even at very high speeds, like 240 kms/h in the Highway

In circuit the common wisdom here is to use more pressure, like 8-10 lbs more (cold), I know is totally different to what you do in EEUU, but we do it this way and it goes well, it comes from the times when we were racing very long distance races in the roads ( in the 60s and 70s) with highly modified street cars....

 

That's very strange Henry. If you put the tire up by 10 lbs when cold, I guarantee that if you measure the pressure after coming off a dozen hot laps that a rear tyre will be 50+ lbs. That would be very scary IMO. You will lose grip because you will only be using the centre portion of the tire as the contact patch. Over inflation will reduce the track ware on the edges and is probably why the racers did it.

 

No not senile, but maybe not a "Porsche" tire guru... those pressures sound like pressures for 16", not 17". Just checked the engine compartment sticker (my '90 that came with 16's) says 36 ft/ 44 rr (cold).

I run 36 PSI all around with my 17's (205/255). What interesting, the tire guru's over at TireRack shipped my wheels (when upgrading to 17's) at 36 all around. Nice attention to detail TR!

 

Guys,

Old thread but hope someone can advice... I currently running 245/45/17 and 315/35/17 tires on my 964 and nobody seems to have an idea on the correct tire pressure I should be running on. Hot and cold. Any expert advice greatly appreciated.

Thanks!

 

I run 2.7 bar front and rear....Porsche says 3.0 for the rear, but I want to keep my false teeth in

 

36 front and 38 rear (cold) w michelin Pilot Sport's on cup 1 wheels...

In my car with my setup, this seems to be a good compromise cold pressure for street use. The car is well balanced and I get decent mileage and tire wear. (Seems)

Try some different things with your car. see what you like. My guess is that when you pump them up as high as your mech says, you will have less grip and the tires will be much much louder inside the cabin...those presures cold just seem way high to me...but all tires are different, outside climates are different, swaybars and alignment, shocks, struts, springs, all are different - so those pressures may be good for me and not good for you...you just have to be within a certain range and then play around a bit...see what you like best...