[ztjjones]

Hello all, new member/poster. I have a '69 Grand Prix and have a friend willing to give me a good deal on a set of 20" rims. I was wondering if anyone has pictures with 20" rims and any advice on rubbing/fitting issues. Thanks!

[Steve C.]

Similar size car....

https://www.youtube.com/watch?v=tnKc3h6g2Jg

I can't confirm if these are 20-inch... but in the opinion of many the music will be appropriate for this "wagon wheel" style !


http://www.bigwheels.net/index.php?l..._wheel=popular


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[72LuxuryLeMansLa.]

I equate putting this size wheel on a classic car to a guy walking around in a nice business suit while wearing those big floppy clown shoes!

[Mace1971]

These wheels don't work on older cars because the proportions are so far off. Modern cars can get by with larger wheels because they're designed for them. The car can sit lower even with larger wheels because the top of the wheel well and the suspension are raised (I guess you can consider that the car is lowered relative to the axles) to prevent the wagon wheel style Steve C mentions. Overall, it's extremism for extremism's sake.

[694.1]

I have pictures...In my head.
It's not pretty.
Stick around here, kid & we'll steer you right!
And Welcome. You are off to a good start.

[JLMounce]

Here's a 72 with 20" wheels. Not quite your car, but should give you an idea.



One thing to note about wheels and classics is that by and large classic cars had fenders cut for smaller overall diameter wheel/tire packages. Most modern cars run around with at least a 28" tall package between the wheel and tire, while most classics were at around 26" total. This changes the "perception" of how big the wheel is and as a result you can get a similar look on classics without having to go as large.

As an example, here's my 1969 Firebird which currently wears 17" wheels with a 26" tall tire. 17" wheels by modern standards are small at this point, but because this car originally had 14" feels from the factory, they look large.



For cars that had 14/15" factory wheels, a 20" wheel represents a +5 fitment which IMHO looks kinda weird, but that's my opinion only. If you want to keep the overall diameter of the package to keep the car sitting as it was intended, you'll end up with very short sidewall tires. Some like this look, but my opinion is that classics want a little bit of tire.

With all that said, if you like the look of large wheels I feel that an 18" wheel/tire package is the best compromise on looks, performance, price and tire availability.

[b-man]

The 20" wheels on that GP are a nice fit, however the styling of the wheels are all wrong.

Plenty of pro touring cars are sporting 20" and even 22"' but the styling is the key along with stance.

[JLMounce]

Originally Posted by b-man

The 20" wheels on that GP are a nice fit, however the styling of the wheels are all wrong.

Plenty of pro touring cars are sporting 20" and even 22"' but the styling is the key along with stance.

I agree, I hate those foose wheels myself, but they're extremely popular for some reason.

[Nicks67GTO]

20s are fine on big cars. Just make sure you get the stance right or it will look silly. The 18s on my GTO are perfect.....though i'm sure lots of the old school guys hate them. I don't really care.

[72projectbird]

GP's on bigger wheels look very good imo.

Go for it!

[Scarebird]

If you are to do this - step up to the ATS spindles also...

http://www.speedtechperformance.com/...rod/prd136.htm

[steve]

I'm sorry I'm from the camp that thinks this look is like a "handicapped" or "hobbled" car. I wouldn't go bigger than 17" JMO

[Blued and Painted]

If they are steel 20's, they will be crazy heavy. Well at least its un-sprung weight. Then a 35 aspect ratio and you will feel every grain of sand on the road. If you hit a pot hole your out 1 tire and 1 rim. Maybe 2.

Guess i'm not a fan.

[Steve C.]

Related to the subject Blued and Painted brings up. This from Popular Hot Rodding magazine.....

"Wheels: How big is too big?

The general rule is to only use as big a wheel as you need to clear brakes and suspension components. The weight of an average car for road racing usually requires brakes that are too big to fit inside 15-inch wheels, so larger ones are used.
So the question becomes what is the best size wheel to use ? It's natural for us to think that bigger is better, and it's true that the general public prefers the look of larger wheels, but don't let that trick you. Oversized wheels will slow you down. It all comes down to moment of inertia. The excess weight of a larger wheel is an important issue, but the diameter of it is a much more important factor. The effect of a 10-pound weight at the end of a 12-inch string is much less than a 10-pound weight at the end of a 36-inch string. The larger-diameter wheels are not only heavier, but are much harder to control the rate of rotation like the weight at the end of the string.
Now let's look at overall tire diameter and the effects of sidewall flex. Let's say you've decided on a tire diameter and are looking at what combination of wheel diameter and sidewall height to run. The taller the sidewall, the more flex it can have. This is a good and a bad thing, but mostly a bad thing. When the sidewall id tall, it can deflect quite a bit, throwing away any sense of your suspension alignment settings. Too short of a sidewall a sidewall can be oversensitive to surface conditions, and gives you far less warning before traction is lost. The trick is to find the right balance.
The sweet spot for most of our muscle cars and track cars is 17- or 18-inch wheels. this isn't just our opinion, but that of many industry insiders. The 12- or 13-inch rotors usually chosen by the road racing crowd fit in these wheels just fine, and don't need the additional clearance given by a 19-inch or larger wheel. Consistent with that, BFGoodrich doesn't even make their sticky road race R1 tires for any wheel larger than 18 inches in diameter.
So why does NASCAR still use 15-inch wheels ? The rules mandate these 15-inch wheels and have for many years; knowledgeable fans speculate that this rule won't change. It can be argued, however, that oval track cars use this tall sidewall as a part of their tunable suspension. Since their quickness is defined by how they can plant power out of the turns, tire pressure can be used to improve that.
That brings us to ask why new Corvettes and Vipers use such large wheels. The simple answer to that is because they look cool. There is no advantage to these larger wheels except their looks. The laws of physics would suggest that using a smaller wheel while still clearing the brakes would make the car faster.


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[HWYSTR455]

One thing to keep in mind is that when you go bigger on wheels, the 'lever' action it creates mandates larger brakes to provide the same stopping power.

When folks add larger wheels (not 'rims') to their' SUVs (common upgrade), braking suffers, not to mention roll center (for any vehicle), and roll over becomes a concern. (just ask some of the big sports figures that made national news)

Then there's the whole tire selection aspect of going 'big'. (or 'DONK')

I recall somewhere there was a chart for the lever action as it relates to size of the wheel, or plus size, but it's foggy, never really paid attention to it, since I knew I would never go over an 18.

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[flat-bill]

JMHO, but I like a wheel/tire combination with some tire sidewall . No rubber band tires for me. But I'm old. Run what you like. Billk

[1966socalgoat]

Well I have 20" rims on my gto 255/30 front 275/30 rear. Wasn't looking to get 20's but a junkyard BMW had them, can't complain for $150 for the set! I like them now!

[amcmike]

Originally Posted by Steve C.

Similar size car....

https://www.youtube.com/watch?v=tnKc3h6g2Jg

I can't confirm if these are 20-inch... but in the opinion of many the music will be appropriate for this "wagon wheel" style !

.

Not even close. Those are 24s or 26s!

O.P. 20s pushing it on a Grand Prix. Sidewall starts to get a bit thin. 17s or 18s might work better.

Here's an example on 17s

http://used-vehicle-sales.com/ca/sal...-prix-716.html

[Steve C.]

OK, but 20's are still wagon wheels


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[1966socalgoat]

Yeeeeehaaawww