Tire size options on 40th anniversary?
10-14-2018, 02:22 PM
#1
Tire size options on 40th anniversary?
It is time for new rubber on my 40th.
I am going to go with Michelin.
With the stock rims, I am limited to PS2’s (225-40-18, 285-30-18). There are few tire options in these sizes.
I can purchase Pilot Sport 4S in the following sizes - 235-40-18 and 285-35-18.
The diameter difference is 1.7%
I would rather get the latest Michelin tires rather than the PS2 that may have been manufactured a year or more ago.
Any thoughts or concerns with these sizes?
Thanks
I am going to go with Michelin.
With the stock rims, I am limited to PS2’s (225-40-18, 285-30-18). There are few tire options in these sizes.
I can purchase Pilot Sport 4S in the following sizes - 235-40-18 and 285-35-18.
The diameter difference is 1.7%
I would rather get the latest Michelin tires rather than the PS2 that may have been manufactured a year or more ago.
Any thoughts or concerns with these sizes?
Thanks
10-15-2018, 09:04 AM
#2
Race Car
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i have the 285-35-18 and it can cause ABS faults due to the diameter being too big, especially if say the front tire pressure is low and rear is high, etc. I would not recommend tires that tall.
10-15-2018, 12:21 PM
#3
The 40 used the same wheels as the other 2004 Carrera coupes on 18 inch rims , the are just polished carrera 2 lightweights .
go on tire rack's website enter your car and click on the 18" and you'll find all manner of options . From track tires to daily use
https://www.tirerack.com/tires/TireSearchResults.jsp?tireIndex=2&autoMake=Porsche&autoYear=2004&autoMod el=911+Carrera+Coupe&autoModClar=&frontWidth=225%2F&frontRatio=40&frontD iameter=18&frontSortCode=53650&rearWidth=285%2F&rearRatio=30&rearDiamete r=18&rearSortCode=54500
im running dunlop direzza zii star spec tires
The best time to look for tires is in the late spring , tire rack has more options from more manufacturers then .this time of the year you get good run out pricing but less options as the manufacturers make limited numbers of 911 sizes .
i also have a set of winters and rims I bought from them in the same size
go on tire rack's website enter your car and click on the 18" and you'll find all manner of options . From track tires to daily use
https://www.tirerack.com/tires/TireSearchResults.jsp?tireIndex=2&autoMake=Porsche&autoYear=2004&autoMod el=911+Carrera+Coupe&autoModClar=&frontWidth=225%2F&frontRatio=40&frontD iameter=18&frontSortCode=53650&rearWidth=285%2F&rearRatio=30&rearDiamete r=18&rearSortCode=54500
im running dunlop direzza zii star spec tires
The best time to look for tires is in the late spring , tire rack has more options from more manufacturers then .this time of the year you get good run out pricing but less options as the manufacturers make limited numbers of 911 sizes .
i also have a set of winters and rims I bought from them in the same size
Last edited by Vancouver996; 10-15-2018 at 09:45 PM.
10-15-2018, 05:15 PM
#4
Rennlist Member
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mdsarch (02-25-2021)
02-24-2021, 12:40 PM
#6
Intermediate
Sorry to resurrect this old thread, but I'm shopping for tires for my 40th. What is on my car today are Sumitomo 295/30/18 in the rear and 225/40/18 in the front. The manual says 225/40/18 front and 285/30/18 rear "or" 225/40/18 front 295/30/18 rear. There is nothing special indicated for the 40th, but I read somewhere that these cars originally came with Pirellis unique to the 40th. To further confuse matters, different tire fitting sites (Michelin, tire rack, etc.) show different combinations, including 235/40 for the fronts.
I'm a little reluctant to go back to Sumitomo because one rear tire has a blistered inner side wall (tires have 10k miles in 10 years). Anyone know what was originally on these cars - or am I overthinking this? Also might be worth noting that the speedo reads a few mph high, so that makes me reluctant to go to 285s in the rear.
I'm a little reluctant to go back to Sumitomo because one rear tire has a blistered inner side wall (tires have 10k miles in 10 years). Anyone know what was originally on these cars - or am I overthinking this? Also might be worth noting that the speedo reads a few mph high, so that makes me reluctant to go to 285s in the rear.
02-24-2021, 01:15 PM
#7
I've been running 235/40/18 front and 295/30/18 rear for about 5k miles now and not a single issue. I would actually like to try 285/35/18 in rear next time as I'd like some extra sidewall there. Pretty sure there are some members that have ran this set up. I went with General G-Max at the time and have been very happy. I'd like to try some Michelin rubber in future.
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robw33 (02-24-2021)
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02-24-2021, 02:51 PM
#8
I thought I had read a previous thread on people running PS4's on 996's, I need new tires on my car this year and planned to try the PS4's but didn't realize they didn't have the 30 ratio rear
02-24-2021, 03:05 PM
#9
02-24-2021, 07:23 PM
#10
Intermediate
Out of curiosity, I looked into the specs of the Pilot Sport 4S relative to the Pilot Sport 2 for rear tires
PS4S: 285/35/18 has 25.9" diameter, 804 revs per mile. At 800 RPM for the wheel, speed would be 59.7 MPH (I know the math isn't really that simple)
PS2: 295/30/18 has 25.5" diameter, 817 revs per mile. At 800 RPM speed would be 58.8 MPH
PS2: 285/30/18 has 24.8" diameter, 840 revs per mile. At 800 RPM speed would be 57.1 MPH
Since our speedos tend to report more MPH than actual, I suspect the PS4S with the 285/35 thicker sidewall will get you a more accurate speedo. Maybe Porsche calibrated the speedos based on tires delivered. I think the C4S and 40th used the 295/30/18 tires, while the standard Carrera used 285/30/18 - but that is part of the mystery I'm trying to solve.
PS4S: 285/35/18 has 25.9" diameter, 804 revs per mile. At 800 RPM for the wheel, speed would be 59.7 MPH (I know the math isn't really that simple)
PS2: 295/30/18 has 25.5" diameter, 817 revs per mile. At 800 RPM speed would be 58.8 MPH
PS2: 285/30/18 has 24.8" diameter, 840 revs per mile. At 800 RPM speed would be 57.1 MPH
Since our speedos tend to report more MPH than actual, I suspect the PS4S with the 285/35 thicker sidewall will get you a more accurate speedo. Maybe Porsche calibrated the speedos based on tires delivered. I think the C4S and 40th used the 295/30/18 tires, while the standard Carrera used 285/30/18 - but that is part of the mystery I'm trying to solve.
02-25-2021, 10:22 AM
#11
Out of curiosity, I looked into the specs of the Pilot Sport 4S relative to the Pilot Sport 2 for rear tires
PS4S: 285/35/18 has 25.9" diameter, 804 revs per mile. At 800 RPM for the wheel, speed would be 59.7 MPH (I know the math isn't really that simple)
PS2: 295/30/18 has 25.5" diameter, 817 revs per mile. At 800 RPM speed would be 58.8 MPH
PS2: 285/30/18 has 24.8" diameter, 840 revs per mile. At 800 RPM speed would be 57.1 MPH
Since our speedos tend to report more MPH than actual, I suspect the PS4S with the 285/35 thicker sidewall will get you a more accurate speedo. Maybe Porsche calibrated the speedos based on tires delivered. I think the C4S and 40th used the 295/30/18 tires, while the standard Carrera used 285/30/18 - but that is part of the mystery I'm trying to solve.
PS4S: 285/35/18 has 25.9" diameter, 804 revs per mile. At 800 RPM for the wheel, speed would be 59.7 MPH (I know the math isn't really that simple)
PS2: 295/30/18 has 25.5" diameter, 817 revs per mile. At 800 RPM speed would be 58.8 MPH
PS2: 285/30/18 has 24.8" diameter, 840 revs per mile. At 800 RPM speed would be 57.1 MPH
Since our speedos tend to report more MPH than actual, I suspect the PS4S with the 285/35 thicker sidewall will get you a more accurate speedo. Maybe Porsche calibrated the speedos based on tires delivered. I think the C4S and 40th used the 295/30/18 tires, while the standard Carrera used 285/30/18 - but that is part of the mystery I'm trying to solve.
02-25-2021, 11:30 AM
#12
Rennlist Member
Thanks for insight. Anybody else have this issue.
I have an 02 C2 and have been running multi-sets of the stock size 285-30-18 tires on the rear but just like all of us, having a difficult time finding tires, and have been eyeballing moving to 285-35-18 in the rear, or even 295-30-18.
Any feedback on ABS issues, handling characteristics, or anything, from anyone running either would be greatly appreciated.
Thanks!
