Question:

I just purchased a new set of Conti ExtremeContact 205×55x15’s for my 325is with the old style Zender two-piece 7×15 competition wheels.  The dealer told me that the pressure rating on the tire case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard.   Take it for granted that I drive hard.  What’s your opinion on this Don Decker

Response:

> I just purchased a new set of Conti ExtremeContact 205×55x15’s for my

325is with the old style > Zender two-piece 7×15 competition wheels.  The dealer told me that the

pressure rating on the tire > case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard. > Take it for granted that I drive hard.  What’s your opinion on this > Don Decker

10 PSI should suit you LOL

Response:

> I just purchased a new set of Conti ExtremeContact 205×55x15’s for my

325is with the old style > Zender two-piece 7×15 competition wheels.  The dealer told me that the

pressure rating on the tire > case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard. > Take it for granted that I drive hard.  What’s your opinion on this > Don Decker

35 lbs. is very low for maximum pressure.  The Conti Sport Contact II’s on my 328i allow for 51 psi, with a limit of 40 psi for seating the bead. "Sport" driving normally calls for more, not less pressure for best handling.  Why don’t you start with the pressures recommended on the door plaque & adjust upwards from there for a ride/handling balance which best suits you? Tom

Response:

Try looking at some comments on the tire rack site for others that use the same tire.  Might find some good advice.  35# sounds awful low for Max tire pressure.  Dealers must also think of lawsuits for tire recommendations due to recent events (Ford).  I never trust the dealers anyway, unless it is the TireRack.  Great company. Go to Conti’s web site also. Al

> I just purchased a new set of Conti ExtremeContact 205×55x15’s for my

325is with the old style > Zender two-piece 7×15 competition wheels.  The dealer told me that the

pressure rating on the tire – Hide quoted text — Show quoted text -> case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard. > Take it for granted that I drive hard.  What’s your opinion on this > Don Decker

Response:

> I just purchased a new set of Conti ExtremeContact 205×55x15’s for my

325is with the old style > Zender two-piece 7×15 competition wheels.  The dealer told me that the

pressure rating on the tire > case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard. > Take it for granted that I drive hard.  What’s your opinion on this > Don Decker

Hard drivers need more pressure not less.  More will help the tire hold it’s shape under the stress of hard driving, less will allow it to deform and wear unevenly.  We are not talking drag racing here of course, but cornering. Local driving schools recommend 40psi for the day on the track for those runnign 33 to 35 pounds normally. -Russ.

Response:

According to the manual, nominal tyre pressure for those size tyres on a 3 series are 2.1 bar(29.5psi) front and 2.4 bar (34psi) rear. This is increased slightly for high speed or heavy loads.

> I just purchased a new set of Conti ExtremeContact 205×55x15’s for my

325is with the old style > Zender two-piece 7×15 competition wheels.  The dealer told me that the

pressure rating on the tire – Hide quoted text — Show quoted text -> case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard. > Take it for granted that I drive hard.  What’s your opinion on this > Don Decker

Response:

– Hide quoted text — Show quoted text -> I just purchased a new set of Conti ExtremeContact 205×55x15’s for my > 325is with the old style > Zender two-piece 7×15 competition wheels.  The dealer told me that the > pressure rating on the tire > case (35#) is the maximum rated psi.  That I might like to reduce this if > (Heh) I drive hard. > Take it for granted that I drive hard.  What’s your opinion on this > Don Decker > Hard drivers need more pressure not less.  More will help the tire hold it’s > shape under the stress of hard driving, less will allow it to deform and > wear unevenly.  We are not talking drag racing here of course, but > cornering. >  agreed, but only to a limit. too little pressure will cause tyres to

derform. but slightly lower pressure will increase traction as more tyre surface will be in contact with the road.too little presure will increase friction further leading to increased rolling resistance and heat build up, therefore if you intend to drive fast for long periods I would IMHO advise adding a little air to prevent this.Adding too much will over inflate the tyre causing less surface contact and less friction/traction and also ruin the ride. Use the manual or plate inside the drivers door to set your tyre pressure. 35 psi sounds very low for a max pressue!! – Hide quoted text — Show quoted text -> Local driving schools recommend 40psi for the day on the track for those > runnign 33 to 35 pounds normally. > -Russ.

Response:

That is the max pressure at the max weight, you want considerably less than this for daily driving.

> I just purchased a new set of Conti ExtremeContact 205×55x15’s for my

325is with the old style > Zender two-piece 7×15 competition wheels.  The dealer told me that the

pressure rating on the tire – Hide quoted text — Show quoted text -> case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard. > Take it for granted that I drive hard.  What’s your opinion on this > Don Decker

Response:

>I just purchased a new set of Conti ExtremeContact 205×55x15’s for my 325is with the old style >Zender two-piece 7×15 competition wheels.  The dealer told me that the pressure rating on the tire >case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard.   >Take it for granted that I drive hard.  What’s your opinion on this >Don Decker

 The max pressure listed on a tire’s sidewall is the maximum recommended for seating the tire bead to the rim when mounting the tire to the wheel.  It is not intended to be used as the actual running road pressure.  You’re supposed to use the pressures listed on the sticker affixed to the car’s doorjam or fuel filler door and not what’s listed on the tire.   When going to larger wheels and tires you’re still supposed to stick with the sticker’s settings,  but adding a pound or two is ok if you drive hard on the streets and canyons.   I have larger tires than stock and run them a few pounds higher than stock pressures and the tires don’t roll over at all even when fully attacking my favorite canyon roads and offramps.  Autocross and track duty are a whole nuther story, but for the street stick with stock pressures or slightly higher if you want to stiffen them up a bit. Randy 89 325is weekend autocross/canyon car Super stiff suspension and 225/50-15’s on 7.5" Alloys http://home.earthlink.net/~randylwalters/

Response:

Whimsy, Randy has laid out the story exactly as I see it.  I use that strategy even if the tires are plussed on stock wheels.  On our Saab 9/5 wagon I put 225/50/16 SP5000 all seasons instead of 215/55/16 as stock.  At doorplate pressures we had no problems for 20k miles until just a few weeks ago, when I found the tread was gone at all the front tire edges.  Turns out to be due to cornering (duh!), not rotating, and I think too little pressure.  I’m raising the pressure about 4 psi all around to move the wear pattern toward the center, and to help keep the sidewalls straight.   Don’t plan to moderate my driving style. That will get the cold pressures up to about 36 psi.  The doorplates recommend 32 psi, and the sidewalls are marked 51 psi max.  So this sounds safe to me.  The ride is a little choppy, but still a great car. This pressure increase hasn’t been necessary on my E36 with the same tires. Must be the better suspension and weight distribution. By the way, the Ford Explorer tire problems were due more to under-inflation, not over inflation. Ken

>I just purchased a new set of Conti ExtremeContact 205×55x15’s for my

325is with the old style >Zender two-piece 7×15 competition wheels.  The dealer told me that the

pressure rating on the tire – Hide quoted text — Show quoted text ->case (35#) is the maximum rated psi.  That I might like to reduce this if (Heh) I drive hard. >Take it for granted that I drive hard.  What’s your opinion on this >Don Decker >  The max pressure listed on a tire’s sidewall is the maximum > recommended for seating the tire bead to the rim when mounting > the tire to the wheel.  It is not intended to be used as the actual > running road pressure. >  You’re supposed to use the pressures listed on the sticker affixed > to the car’s doorjam or fuel filler door and not what’s listed on the > tire.   When going to larger wheels and tires you’re still supposed > to stick with the sticker’s settings,  but adding a pound or two is > ok if you drive hard on the streets and canyons.   I have larger > tires than stock and run them a few pounds higher than stock > pressures and the tires don’t roll over at all even when fully > attacking my favorite canyon roads and offramps. >  Autocross and track duty are a whole nuther story, but > for the street stick with stock pressures or slightly higher > if you want to stiffen them up a bit. > Randy > 89 325is weekend autocross/canyon car > Super stiff suspension and 225/50-15’s on 7.5" Alloys > http://home.earthlink.net/~randylwalters/

Response:

– Hide quoted text — Show quoted text -> Whimsy, Randy has laid out the story exactly as I see it.  I use that > strategy even if the tires are plussed on stock wheels.  On our Saab 9/5 > wagon I put 225/50/16 SP5000 all seasons instead of 215/55/16 as stock. At > doorplate pressures we had no problems for 20k miles until just a few weeks > ago, when I found the tread was gone at all the front tire edges.  Turns out > to be due to cornering (duh!), not rotating, and I think too little > pressure.  I’m raising the pressure about 4 psi all around to move the wear > pattern toward the center, and to help keep the sidewalls straight. Don’t > plan to moderate my driving style. > That will get the cold pressures up to about 36 psi.  The doorplates > recommend 32 psi, and the sidewalls are marked 51 psi max.  So this sounds > safe to me.  The ride is a little choppy, but still a great car.

Couldn’t agree more. I’ve kept the (recommended 32 psi) pressures on my wife’s 9/3 convertible at about 34-35. The slight tradeoff in ride firmness is more than made up by the improved handling, and the projected tread life on the OEM Michelin XVS "all seasons" will be about 45,000 – with rotation every 10,000. Tom

Response:

I worked around several pressure settings to 41# front and 44# rear.  Ride is firm and solid now. (the Conti’s are rated at 44#)  I tried 44# in front for a time then reduced it a bit to 41#. 1989 325is. DDecker – Hide quoted text — Show quoted text -> > I just purchased a new set of Conti ExtremeContact 205×55x15’s for my > 325is with the old style > > Zender two-piece 7×15 competition wheels.  The dealer told me that the > pressure rating on the tire > > case (35#) is the maximum rated psi.  That I might like to reduce this >if > (Heh) I drive hard. > > Take it for granted that I drive hard.  What’s your opinion on this > > Don Decker > Hard drivers need more pressure not less.  More will help the tire hold >it’s > shape under the stress of hard driving, less will allow it to deform and > wear unevenly.  We are not talking drag racing here of course, but > cornering. >  agreed, but only to a limit. too little pressure will cause tyres to >derform. but slightly lower pressure will increase traction as more tyre >surface will be in contact with the road.too little presure will increase >friction further leading to increased rolling resistance and heat build up, >therefore if you intend to drive fast for long periods I would IMHO advise >adding a little air to prevent this.Adding too much will over inflate the >tyre causing less surface contact and less friction/traction and also ruin >the ride. >Use the manual or plate inside the drivers door to set your tyre pressure. >35 psi sounds very low for a max pressue!! > Local driving schools recommend 40psi for the day on the track for those > runnign 33 to 35 pounds normally. > -Russ.

Response:

> I worked around several pressure settings to 41# front and 44# rear.  Ride

is firm and solid now. > (the Conti’s are rated at 44#)  I tried 44# in front for a time then

reduced it a bit to 41#. > 1989 325is. > DDecker

If you notice the tread is wearing faster in the center than on the shoulders, you have too much air. I think you have way too much air, by about 11 and 14 pounds front and rear, respectively. I am not familiar with the tires and rime that you have, or hte kind of driving you do, but just by looking at the numbers, I say you have too much air in them. Use some sidewalk chalk and draw a patch on your garage floor, then drive over the patch and observe the tire marks in the chalk.

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