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How do tires & rims work a brief tutorial (2nd attempt) . . .

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Okay kids.



Since lots of us (including myself) are visual people.



Here's a nice diagram about how your rims and tires work.




For starters, when buying a tire:



They have these sizes:



245/50R16 (example of TGP/GTP x-lace tire size)

225/60R16 (example of Cutlass Supreme 5-spoke/sawblade standard tire size)


The first number is the Treadwidth - Look on the pic.

The second number is the percentage of the treadwidth on the sidewall on the 225/60R16 example 135mm would be the sidewall size or (135/225 = 60% or .6)

The third number is the diameter of the rim.




Now on the rims. This affects 1st generation rims more than seconds.



There are two big fat short red lines on the drawing. These are the two key dimensions when buying rims for your car. Assuming that you have got the bolt pattern to match and the right size (diameter rims).


Offset, if you buy rims with the wrong offset they will stick out or in from the car, the higher the offset the more it sticks in. The lower the offset the more it sticks out (all other things being equal). If you have rims that stick too far out or in. You will start having performance or rubbing issues.


Backspacing,if the diagram above doesn't help out as much as needed. Backspacing is the distance between where the wheel mates with the hub on the car, compared to where the back facing of the spokes on the rim. The issues that first gen W-bodies have is that if you don't have sufficient backspacing REGARDLESS of the offset of the rims, you will NOT clear the brake calipers on the front. If you do happen to make the mistake of buying rims which will not clear, you will be forced to add spacer plates, bolt-on spacers or a combination of longer wheel studs with spacer plates (all very undesirable options).



If you have any questions, I'm not a specialist, but I'll try to help there's lots of others here who can do the same. Happy rim hunting, and car driving.

Edited by Breakdown
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I guess I'm not normal :shrug:. Long before I worked in tires I made it a point to call them wheels, NOT rims...


Geez, maybe I should have said "typical" person. :)

Because, yes, if you get someone that doesn't speak English, they won't call them "rims", but they could be 100% "normal". Hmm, is anyone 100% normal? :dunno:

Edited by Cutlass350
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