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Discussion Starter #1
There are SO many reasons not to put oversized rims on a car. The 400/CGT came with 14" rims so 20"s would be a +6 fitament. That's insane. First you will absolutely kill the ride. Second, you'd have a SMALLER contact patch...the size you would need is 165/30/20 (yes, 165)...and even that would throw a 3% speedo error into the mix. If they made them, the "perfect" size would be 195/20/20 (yes, 20 aspect ratio), but they don't make tires that low profile.
Now, lets assume for a second you decide that you are OK with 165/30/20s...the unspring weight of a 20 is going to be a LOT more than a 14". Every 1# of unsprung weight is = [email protected]# of sprung weight, so it's adding a TON of weight to an already slow car. You thyink your CGT is slow now? Count on the 20s adding at least 1-1.5 seconds to the 0-60 run. Also due to rotational inertia, your braking distances with by exponentially longer (to the point of being dangerous unless you do a big brake upgrade at the same time).
OK, so 20s are a BAD idea...so whjat's a good idea? Well, for performance, you want 15s or MAYBE 16s...anything bigger is 100% pure BLING. Now, if you really like the looks of chuck wagon wheels with rubnber bands...then go for 17s. With 17s you'd be ruinning a 205/35/17 tire, you can't getmuch lower profile than that..
But beware of that even to equal the performance of a 15"...you need a VERY light 17". Why The polar moment of inertia increases with proportion to the square of the radius. So given the same weight, the smaller radius wins. If the 17" wheel is a factor of 1.28 lighter however, they would be even (again, ignoring the moment of the tire). So to equal a 15" wheel which weighs 20 pounds you would need a 15.625lb 17" wheel.
So, if you are looking for best performance, go for 15", best ccombination of looks/perfomance go with 16" and for bling bling looks, go for 17s...
 

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Re: (eurowner)

As someone with 16's on his CGT, I agree!

The extra weight of the bigger wheels (11 lbs per corner!) is not helping my acceleration times, and I'm actually considering a set of 15" for track use.
 

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Re: (eurowner)

Quote, originally posted by eurowner »
You only have about 120 hp, why waste it?

If your rolling with a stock I5 (100-130 hp depending on which motor you have) 17"s are not a great idea for weight reasons. However, that is not to say it has not been done, nor will your car be a death trap due to having them.
I have a 220hp MC1, 17"s with 205/40-17s and they barely affected my performance (my butt dyno says so
) plus they look and ride awesome. http://****************.com/smile/emthup.gif
J.






Modified by 84cgtturbo at 11:11 AM 10-2-2006
 

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Re: (VR6GTI72)

Quote, originally posted by VR6GTI72 »
I hope to see that car lowered a little more when show season hits

No need to be lowered anymore than it is... unless you want him to crack the front spoiler some more....
 

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Re: (nodq)

Quote, originally posted by nodq »

No need to be lowered anymore than it is... unless you want him to crack the front spoiler some more....

I didnt say that because I thought it was practical....I wasnt meaning leaving it that way either..its just for a show or photos...then turn them up for the rest of the year. Might as well take advantage of the adjustability even if its only once.
 

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unless he did some mods, you can't lower the front much more than is shown. My GT is on the lowest setting in front. Any lower, and you'd need shorter (6 or 7 inch) springs with shortened shaft shocks. My car looks - essentially - the same as his. But more stealth, and less spokes
 

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Re: (Audi Coupe GT)

Quote, originally posted by Audi Coupe GT »
unless he did some mods, you can't lower the front much more than is shown. My GT is on the lowest setting in front. Any lower, and you'd need shorter (6 or 7 inch) springs with shortened shaft shocks. My car looks - essentially - the same as his. But more stealth, and less spokes


Actually, when I had the coilovers installed I had the car raised about 1/4" (plus the 1/2" the wheels added). This was done deliberately so that I can clear my driveway at home without scraping off my front spoiler. There is some adjustment left if I wanted to lower it more, I just don't want to at this time.
J.
 

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Re: (84cgtturbo)

I'm looking into either 15's or 16's... Any comments on ride quality differences between 205-50-15's and 205-45-16's? I want to keep the ride somewhat civilized, but still look nice... Probably will be type-E's in either size. BTW, I'm running Bilstein HD's and H&R Sports...
 

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Huh - must have gone with 7 inch springs? My front will not go any lower, but I had to raise the rear 1/2 an inch to clear the 225's, which still rub (doh!) on track in 1+ g corners.
 

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Discussion Starter #12
Re: (Krautwagen)

Quote, originally posted by Krautwagen »
I'm looking into either 15's or 16's... Any comments on ride quality differences between 205-50-15's and 205-45-16's? I want to keep the ride somewhat civilized, but still look nice... Probably will be type-E's in either size. BTW, I'm running Bilstein HD's and H&R Sports...

My first comment would be that 205-45-16 is the wrong size for a 16. You want 215/40/16 is you go 16s. Check out http://www.miata.net/garage/tirecalc.html You want to keep the %error as low as pssible. 205/45 creates a 2.5% error, 215/40 creates a 0.1%...almost perfect.
 

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Re: (84cgtturbo)

I ran 205-40-16's on a rabbit once... never again. I am wary of anything less than a 50 series...
 

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Re: (Krautwagen)

for sport and styling here is what I did when I had my coupe...(i've since sold it for a newer, more powerful mk3 golf. but 15" is more than plenty for the CGT
my point:

FYI: borbet type E 15x7 35 ET with toyo T1S 195/50/15...great ride and tons of grip with no noticible power loss.
 

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Re: (duandcc)

Quote, originally posted by duandcc »

My first comment would be that 205-45-16 is the wrong size for a 16. You want 215/40/16 is you go 16s. Check out http://www.miata.net/garage/tirecalc.html You want to keep the %error as low as pssible. 205/45 creates a 2.5% error, 215/40 creates a 0.1%...almost perfect.

Dave, 195-60-14 is the stock size for a '86 4kQ, 205-45-16 is only a .2% error. Error doesn't matter as much to me a rubbing does anyway. Thanks for the link to the great resource though
 

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Discussion Starter #18
Re: (Krautwagen)

Quote, originally posted by Krautwagen »
Dave, 195-60-14 is the stock size for a '86 4kQ,

Oops
Yeah, OK...my bad...
 

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i'm running 205 50 15's falkens on my speedline alloys. just wondering what is the largest width i can get on my wheels ? (and/or under the arches for that matter)
 

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Re: (MGaz)

Silly Dave
. I'm running 17's with a 215/40/17 and man I love um. The ride is a little more rough but nothing too bad and the wheels are on the heavy end of the spectrum but man the look and cornering ability is well worth it.
 
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