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tHi does anyone know how wide of rim that will fit on a 66 GTO? And know what off set you can use on the front and back with out them rubbing? Thanks
 

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I know on the rear you should be ok. The concern is the front, especially with 15 inch rims. RMTZ67 has a nice setup on his 67 he or Lemans guy could tell you. Minesa66 too
 

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I had a 9.5 wheel w/ a 4.5 offset and a 255/40/17 on the rear and always rubbed. Even with massaging the inner fender well and trimming. I now have 8"wheels all around....same offset and tires. Not as much of a rub on a lean but still there. 8" 4.5 Offset and 245 tires would be ideal. I thought I read a article that 14/15" tires of the same width were actually wider. What are you looking as far as height in your wheels?
 

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From an ex-wheel bearing engineer: Please put an offset on your front wheels - the bearing suppliers will thank you.

I think you'll actually get away with it longer on cars with tapered roller bearings for a couple reasons but it's murder on the newer cars with preloaded ball bearings. On the other hand, if you don't put a lot of miles on it (i.e., it's not a daily driver) or don't mind changing bearings more frequently, go for it.

Here are the details....

On a solid rear axle it may be less of an issue. I didn't work on solid axle bearings. On the other hand, when it's not a solid axle the bearings are designed so the load goes more or less through the center of the bearing assembly and splits the forces between the inner and outer bearings. In this case there is no torque applied to the individual bearings. However, once the center of force is outside the bearing itself, the bearings now need to resist a torque load as well as the plain upward force.

Here are some diagrams to show the basics of what happens to bearing loads (red) as the wheel load (black) moves out from the center of the two bearings - two bearings make up one "wheel bearing". (click to enlarge):

brg_load_center.png brg_load_1_brg.png brg_load_offset_1.png brg_load_offset_3.png
And note that it has nothing to do with where the wheel mounts to the flange. It's all about the center of the tire patch on the road vs. the center of the bearings. And, of course, this ignores the issues with steering.

I'm not actually trying to discourage anyone from doing it as long as they understand the implications. You WILL have lower bearing life. How much lower depends on how much offset, how much you drive it, and how hard you drive/corner it.

And I hope everybody here knows - do NOT torque tapered wheel bearings! Finger tight is plenty. I was always taught "finger tight while rotating the wheel then back off just enough to insert the the cotter pin." A friend of mine torqued his to 25 ft. lb. and at about 3,000 miles I replaced all 4 bearings for him.
 
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