tire rim size question for a '75 911 (16x6, 16x7)
07-06-2012, 12:06 PM
#1
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tire rim size question for a '75 911 (16x6, 16x7)
I don't have another mid-70's 911 around here to look at, so I was hoping you guys could help me with this-
I have repro Fuchs 16x6 in front and 16x7 in the rear. The PO put 225/50/16 in the back, and 215/55/16 up front. The front clears fine, but the rear tires will not clear the lip, and the car is sitting very high for tire clearance right now... I'd like to buy some new tires and lower the car.
I see that most of you who don't want to roll the fender lip or flare the fender, go with 205/50/16. I'd like to approximate the original overall diameter by going with 205/55/16 instead- I don't race the car, and I do a lot of highway driving, and a little more sidewall would be nice for comfort, but I don't want to do it if I am going to have even more clearance issues...
I know that the 16 x 7's in the rear may cause small clearance issues, and I am prepared to roll the rear fender lip, if that is all that will be needed. The car will require a 4 wheel alignment also, because I am in the process of replacing all my front end hardware right now, so a little negative camber can also be done, provided I know what the max camber adjustment should be for a street car (I know the factory spec's, but I don't know what you guys are running on the street).
Can you see any reason why I cannot or should not go with 205/55/16's over 205/50/16's? Am I just splitting hairs here??
Any and all input highly appreciated
Thanks,
Dave
1975 911S Targa
I have repro Fuchs 16x6 in front and 16x7 in the rear. The PO put 225/50/16 in the back, and 215/55/16 up front. The front clears fine, but the rear tires will not clear the lip, and the car is sitting very high for tire clearance right now... I'd like to buy some new tires and lower the car.
I see that most of you who don't want to roll the fender lip or flare the fender, go with 205/50/16. I'd like to approximate the original overall diameter by going with 205/55/16 instead- I don't race the car, and I do a lot of highway driving, and a little more sidewall would be nice for comfort, but I don't want to do it if I am going to have even more clearance issues...
I know that the 16 x 7's in the rear may cause small clearance issues, and I am prepared to roll the rear fender lip, if that is all that will be needed. The car will require a 4 wheel alignment also, because I am in the process of replacing all my front end hardware right now, so a little negative camber can also be done, provided I know what the max camber adjustment should be for a street car (I know the factory spec's, but I don't know what you guys are running on the street).
Can you see any reason why I cannot or should not go with 205/55/16's over 205/50/16's? Am I just splitting hairs here??
Any and all input highly appreciated
Thanks,
Dave
1975 911S Targa
07-06-2012, 12:44 PM
#2
Former Vendor
A 225 should fit with the lips rolled. Sounds like the wheel offset is a bit low.
215/50 16 should work out back without making you do the roll work. It's a half inch skinnier and shorter than where you are at now. I have Dunlop DZ101's in a match 205/215 combo.
Let me know if interested.
215/50 16 should work out back without making you do the roll work. It's a half inch skinnier and shorter than where you are at now. I have Dunlop DZ101's in a match 205/215 combo.
Let me know if interested.
07-06-2012, 03:01 PM
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Hmmm..Well, here's where I'm at with 225/50 in the back-I am sure these 7" rims will rub with 215's after I lower it. This a view of the rear wheel looking down and 3/4 view, and I have about 22 mm of tire tread extending outwards from the inside of the lip right now...
I can see that the 215's would work in the back if they were mounted on 6" rims, but the 7" rims really seem to push the tires out.
Of course, I have no idea yet what happens when you lower the car- does the suspension travel inwards (slightly?) as well as upwards? If the wheel moves inwards even 10mm when the suspension compresses, then I should be okay with 215's...
Thanks for your input!
Dave
1975 911S Targa
I can see that the 215's would work in the back if they were mounted on 6" rims, but the 7" rims really seem to push the tires out.
Of course, I have no idea yet what happens when you lower the car- does the suspension travel inwards (slightly?) as well as upwards? If the wheel moves inwards even 10mm when the suspension compresses, then I should be okay with 215's...
Thanks for your input!
Dave
1975 911S Targa
Last edited by MillenniumFalcon; 07-06-2012 at 03:22 PM.
07-06-2012, 03:17 PM
#5
I haddah Google dat
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You might want to try more negative camber.
Why are you going with wider tires at the rear? Porsche didn't start with the wider rear tires until the motors got heavier, and started producing a lot more torque. If you had say a 3.0 911SC motor in there, then you might burn off 205s and would need 215s or 225s.
To answer your question, yes the top of the tire definitely moves inward. You might even have 10mm more clearance at ride height. If not, then you can go with stiffer rear bars, more negative camber, or a different profile tire (different manufacturer).
Why are you going with wider tires at the rear? Porsche didn't start with the wider rear tires until the motors got heavier, and started producing a lot more torque. If you had say a 3.0 911SC motor in there, then you might burn off 205s and would need 215s or 225s.
To answer your question, yes the top of the tire definitely moves inward. You might even have 10mm more clearance at ride height. If not, then you can go with stiffer rear bars, more negative camber, or a different profile tire (different manufacturer).
07-06-2012, 04:02 PM
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Rusnak,
Thanks for your input. Understood.
I have wider rims in the back because that is what came on the car. I don't have the coin for new rims, so I need to use what I have.... 205 all around is just fine for me. If 215's in the rear would fit, I might want to go that route...because 215's fit in the front just fine on the narrower rim.
On a side note, I think I will be upgrading to a 3.0 in the future, I just don'tknow exactly when.
Thanks for your input. Understood.
I have wider rims in the back because that is what came on the car. I don't have the coin for new rims, so I need to use what I have.... 205 all around is just fine for me. If 215's in the rear would fit, I might want to go that route...because 215's fit in the front just fine on the narrower rim.
On a side note, I think I will be upgrading to a 3.0 in the future, I just don'tknow exactly when.
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07-06-2012, 04:31 PM
#8
The rear wheel well on that car was designed for a 6x15ET36 wheel w/ 185/70 x15 tire
compare that to what you have now 7x16 ET23.3
the tire is actually .34" shorter, so no problem there
the outer edge of the wheel is 25.4mm or 1 full inch further outboard and then the outer edge of the tire is 45.4mm further out than the 185/70 would have been, it just doesn't fit!!! Not unless you add SC/Carrera flares or use a high off set wheel.
the ST's w/ those rear fenders used 7x15ET49 wheels and a spacer which depended on the tire used
a 7x15ET49 would place the wheel lip .3mm further out that the 6 and the inner wheel lip 25.7mm more inboard, the spacer was used to gian inner room at the expense of lip room.
compare that to what you have now 7x16 ET23.3
the tire is actually .34" shorter, so no problem there
the outer edge of the wheel is 25.4mm or 1 full inch further outboard and then the outer edge of the tire is 45.4mm further out than the 185/70 would have been, it just doesn't fit!!! Not unless you add SC/Carrera flares or use a high off set wheel.
the ST's w/ those rear fenders used 7x15ET49 wheels and a spacer which depended on the tire used
a 7x15ET49 would place the wheel lip .3mm further out that the 6 and the inner wheel lip 25.7mm more inboard, the spacer was used to gian inner room at the expense of lip room.
07-06-2012, 05:49 PM
#10
Addict
Click on the link in Bill's signature. Your problem is in the wheel offset, not in the tire size.
http://members.rennlist.com/1976c38/index.html
http://members.rennlist.com/1976c38/index.html
07-06-2012, 08:59 PM
#11
Sell the 7x16s, buy 2 more 6x16s to run in the rear. Run the same size tire all around (say 205-55-16).
lower the rideheight as neede (for a street car, I like the "euro" rideheight) and get the car aligned and cornerbalanced.. Then enjoy!
If you like phonedials, put two late offset 944 7x16s came with a 52mm offset.. just 3mm away from the vaunted 911R wheels (49mm offset) that fit perfectly in the back of a narrow car. But most folks don't seem to like phonedials on a 911..
lower the rideheight as neede (for a street car, I like the "euro" rideheight) and get the car aligned and cornerbalanced.. Then enjoy!
If you like phonedials, put two late offset 944 7x16s came with a 52mm offset.. just 3mm away from the vaunted 911R wheels (49mm offset) that fit perfectly in the back of a narrow car. But most folks don't seem to like phonedials on a 911..
