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Discussion Starter #1
Hello!
Just purchased a 90 Spider and the previous owner put big old 16 inch rims on it with 205/55/R16's on them. Looks great, tasteful rims not all garish, but, on quick right hand turns or when braking hard while turning, the front drivers side catches on the inside of the fender. It's actually beginning to damage the lip. My question is...can I replace the front 205/55/R16's with a narrower and slightly shorter 195/50/R16's and leave the rear larger, like you see on older muscle cars? How would it affect the handling and drivability?
 

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Larger wheels in the back will increase understeer to the point that it will feel like the car is not responding when you are trying to turn. An "understeering pig" I think is the "technical" term... The Spider is built such that the front wheels stick out more than the rear wheels. The front is wider than the back by one inch. With this set-up, you must keep all 4 wheels/tires the same size. The OEM circumference with 15 inch wheels is 24.2 (195/60-15 tires), so 205/55-16 tires are a little large. Nonetheless, I would be more suspicious of the offset of the 16 inch wheels, since it really is no problem to fit 16 inch wheels to a Spider. What brand/model wheels are these?

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Oh, - I just realized that you have a Graduate, which came originally with 14 inch x 5.5 inch wheels, and 185/70-14 tires. It is common for owners to replace these wheels. However, this doesn't change the "plus" size that should be used...

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Enrique nailed the description. An "Understeering Pig" isn't much fun to drive (he may have remembered my use of the term after fitting a big tubular front swaybar without balancing with a stiffer rear bar). However, the biggest thing to remember when fitting larger diameter rims is to use one of the common tire size calculators to determine the overall tire diameter. Using larger rims and retaining the same aspect ratio tires may, as you have found, result in something rubbing. In other words, as the rim diameter increases, the tire aspect ratio must decrease.. This also works just for changing tire sizes on the same wheel; I bought wider tires for my '91 Spider, but changed aspect ratio: from 195/60 to 205/55 assured the overall diameter remained almost exactly the same.

Larger wheels in the back will increase understeer to the point that it will feel like the car is not responding when you are trying to turn. An "understeering pig" I think is the "technical" term... The Spider is built such that the front wheels stick out more than the rear wheels. The front is wider than the back by one inch. With this set-up, you must keep all 4 wheels/tires the same size. The OEM circumference with 15 inch wheels is 24.2 (195/60-15 tires), so 205/55-16 tires are a little large. Nonetheless, I would be more suspicious of the offset of the 16 inch wheels, since it really is no problem to fit 16 inch wheels to a Spider. What brand/model wheels are these?

Best regards,
 

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Discussion Starter #6 (Edited)
Thanks for the info gents. The guy at the tire shop said that the difference in handling would be negligible and in fact may improve it by going with the slightly smaller tire on the front. On one hand, he could have easily gotten me to buy all four and didn't. On the other hand, he may not know what the hell he's talking about. We'll see. I ordered two Falken ZEIX 912 195/50/R16's. At worst, if it feels crappy I'll replace the rear rubber as well and/or throw a stiffer sway bar in the ***-end. I'll keep you posted.
 

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... The guy at the tire shop said that the difference in handling would be negligible and in fact may improve it by going with the slightly smaller tire on the front. On the other hand, he may not know what the hell he's talking about. ...
This is truly a very ignorant assumption, but it's not because he doesn't know his trade, rather it is because he has no idea that the Spider track is wider at the front than at the rear. The narrower/smaller in the front, wider/larger in the back works for many cars, but it is illogical for the Spider design and set-up. It has been tried many times by a lot of people, and no one has reported good results... The good thing is that tires are not particularly expensive and they are easy to change. :)

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Discussion Starter #8
If I put that size tire, 195/50/R16, on all the way around will she handle okay? Or will the slightly different ratio from OEM make it feel lousy? I hope I didn't just flush $250 down the toilet.
 

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... i run 205/50/16 goodyear f1-gs-d3 tire.. works well for me.. steering is not heavy at low speed and still nice and light at road speeds.as for psi? 30 front..33 rear..car seams set up well..just a little understeer, but i can hang out the back when i want to..( yes on quite back roads or at are local auto-crosses)
 

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If I put that size tire, 195/50/R16, on all the way around will she handle okay? Or will the slightly different ratio from OEM make it feel lousy? I hope I didn't just flush $250 down the toilet.
If all the tires are the same size, she will handle just fine. The slightly different ratio will not have a negative effect, and you have not waisted any money. Since you have already ordered the tires for the front you could just have them installed, so you can experience first hand what we've been discussing here. Afterwards, you can install rear tires that match the front ones.

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Discussion Starter #11
The slightly different ratio will not have a negative effect, and you have not waisted any money.


Glad to hear that. One thing that still concerns me is why the driver's side tire was catching the fender lip in the first place. ConeDriver said he's using the same size tires as I and apparently didn't have an issue with them. Are my springs losing their...uh...spring? The shocks are red Koni's that don't appear to be more than a year old. Might i be replacing these nearly new tires for no reason?
 

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George (conedriver) is using a 15 inch rim with a 205/55 tire, which yields a diameter of 23.88 inches. The OEM size tire for his series 4 Spider, which came with the 15 inch wheels that he is still using, is 195/60, or 24.21 inches in diameter. The size wheel that you are using, 16 inch, with a tire that is 205/55 yields a circumference of 24.88 inches. This is a full inch larger than a typical circumference and maybe just large enough to cause rubbing. The space in the front is tight, and it is not unusual for some larger tires to rub. Certainly what you are reporting is not surprising. I would think that if the springs are an issue, you would be able to see or notice that one or both springs are collapsing, and you would be bottoming out at the slightest bump... You may be also able to check the rubbing by turning the wheel fully to either side, while driving at very low speed in a parking lot.

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Discussion Starter #13
Ah...I misread...i thought he was running 16's as well... The only rub i get is when i'm either cornering aggresively or braking suddenly with wheels turned.
Thanks for all the info gentlemen!
 

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Discussion Starter #14
Finally got the tires on. Seems the guy who put these oversized rims on didn't bother to put anti-seize on the wheel studs. Dumbass... One of them broke coming off. Between the holidays, problems with the company we ordered the stud from and my mechanic being buried in work it took this long to get it replaced.

Anyway. Going down to 195/55/16 tires in the front did the trick and i don't notice any difference in the steering. My mechanic said it would only really make a difference were i racing it and needed to shave a few tenths of a second off my time.
 

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on my 205/50/16's i did have a problem with front rubing..i just carfully hammered in the inner fender lip.. nice now.my off sets 45 mm offset, front drive. i run 25mm wheel spacers on the front and 1/4" spacers on the rear...
 
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