9001st wheel offset question (-:

cjpacitto · 03:23 AM

I bought these wheels this past weekend to put on my 87 944 n/a.

9J16ET70 rears and 7J16ET55 fronts.

(The seller was great and gave a very accurate description including the fact that the tires were not in good shape.)

After getting home I started looking for 245/45R16 tires and found the choices to be minimal. I then started learning about wheel offsets. Now I'm wondering if I made a good decision. It appears that these will fit on the car but I'm concerned if they will hurt the performance more than they will help.

The car will be used primarily for fun driving on the weekends but I will also be participating in some autocrosses and eventually some nasa DE events (once all mechanical issues are ironed out). Are these big rear wheels/tires going to significantly adversely effect my handling or will it be ok? I'm wondering if I would be better off selling them and finding a set with 8" wide rear wheels so I can go with 225/50R16's all around.

Any thoughts, suggestions, or experience????

kdjones2000 · kdjones2000's Garage

You bought some very nice 7" and 9" wide wheels.

Get some 205/55/16's or 225/45/16's for the front, and some 225/45/16 or 245/40/16's for the back and you will be fine.

Based on what you wrote above, I strongly suggest going to a local tire shop and letting them choose the correct sizes for you.

Good luck, Keith

924Sman · 08-12-2009, 06:35 PM

I hope the 145 is a typo, perhaps you meant 245....and the ET 70 has me puzzled. That is an offset that is roughly 18mm off your ET 52.3 offset stock. I do not know if there is a Porsche offset at 70?....They do look pretty though. I am assuming those came off a Boxster or Cayman perhaps?

As far as performance the bigger the wheel/tire the more weight you are spinning and in an NA that is not a real good thing. But yes a wide tire is always a good thing provided there is horsepower to make them work.

Dal

Tidybuoy · 01:19 AM

Quote:

Originally Posted by 924Sman

I hope the 145 is a typo, perhaps you meant 245....and the ET 70 has me puzzled. That is an offset that is roughly 18mm off your ET 52.3 offset stock. I do not know if there is a Porsche offset at 70?....They do look pretty though. I am assuming those came off a Boxster or Cayman perhaps?

The 70mm offset was used due to the 9" wheel size. It counter acts the extra inch and prevents the wheel from sticking out a full inch more than the 8" size. The 9" wheels will look wide but will not stick out much more than the normal 8" wheels. I think the 944 turbo clubsport rear wheels were et 65. The 65 vs 70 et may have to do with the fact that the club sports were thinner, forged alum vs cast wheels.

cjpacitto · 08-13-2009, 03:33 AM

Quote:

Get some 205/55/16's or 225/45/16's for the front, and some 225/45/16 or 245/40/16's for the back and you will be fine.

You can't put 225/24/16 on a 9" wheel. You can't even put 245/50/16 on a 9" wheel. It seems the 245/45/16 is the only tire size that is approved for a 9J16 wheel (based on tire manufacturers specs).

Quote:

I hope the 145 is a typo, perhaps you meant 245....and the ET 70 has me puzzled. That is an offset that is roughly 18mm off your ET 52.3 offset stock. I do not know if there is a Porsche offset at 70?....They do look pretty though. I am assuming those came off a Boxster or Cayman perhaps?

Doh! You are right... I did mean 245. I just edited my original post. The wheels are off a 911/964. A quick check with one of the online offset calcuator shows the 9" 70mm offset wheel will extend 7mm further outwards than stock (no problem there) and 43mm more to the inside (plenty of clearance there too).