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P.Webb
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Post by P.Webb » Wed Dec 29, 2004 5:46 am

Ok fair enough. As I said, you can do an offset/spacer combination to keep the track approximately stock so you don't get rubbing. That's going to depend on the car. I increased the track for running on the race track. My car isn't purely street so don't take my setup as a typical example.

What reservations do you have on lug patterns? Is it just the availablity or some technical reason?

-Peter
The true joy of an Alfa Romeo is behind the wheel.
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Ronal Wheels

Post by hutchensgd » Fri Dec 31, 2004 10:13 am

I was thinking about purchasing a set of rims from Ronal USA. Does anybody have any experience with their products?

I am planning to purchase their R-28 wheels. The tires they are recommending for the car are 205/45/16. I believe some of you guys put wider tires on. What size tires will fit?
Glenn
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Post by 4SFED4 » Fri Dec 31, 2004 12:45 pm

H,

Ronal makes a good product.

I have fit as large as 225/45 16's on 8" rims without rubbing. I do beleive a 245/45 16 would fit... although I have not tried it yet.

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Post by enzo » Fri Dec 31, 2004 1:19 pm

225/45/17 on the rear on 7,5x17 offset 30mm, lowered about 50mm
205/40/17 on the front....no rubbing...



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Post by Micke » Fri Dec 31, 2004 5:02 pm

OK, just a couple of points not ment to offend anybody.

1) the weight of the rims (and/or tires) is interesting. However, the car's performance lies behind the traction. The weight is much, much, much less important. Trust me.

The 75 and the GTV can fit 63 cm tires in the back i.e 225/40R18 , 225/45R17 , 225/50R16. The gear ratios will be a bit long but this again is less important than good tires.

The GTV's can fit the same in the front (mine at least) but the 75 not. You need smaller tires like 215/40R17 or 205/50R16.

Mixing tire tire sizes is OK as long as you know what you do (and don't have traction control like we don't in old Alfas anyway)
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Thanks!

Post by hutchensgd » Fri Dec 31, 2004 7:07 pm

I appreciate your feedback; especially how fast of a response. I guess I will go by what Ronal USA reccomends. I think this is the most prudent based on what I have heard.
Glenn
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Post by jrreeve » Sat Jan 01, 2005 7:36 am

I tend to agree that the performance lies in the tires, but the amount of effort that Alfa went through to keep rotating mass down on the GTV-6 it would be a shame to see heavy wheels on the car. From the superlight stock Campanoglo's to the inboard mounted disc brakes this car is set up for nice light wheels. I like the look of most of the Ronals and what the selection they have for the GTV6 is great, but I still think most of their wheels are a little to heavy for my taste 19-21lbs. Stock Campanoglo's....something like 12lbs. But they are reasonably priced and have a lot to offer.

Rob
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Weight of wheels?

Post by hutchensgd » Sat Jan 01, 2005 3:44 pm

I guess I do not understand the issue with the weight of the wheels. Is this all based on minimizing the total weight of the vehicle to maximize HP / weight, or something else?
Glenn
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Post by 4SFED4 » Sat Jan 01, 2005 6:18 pm

Overall weight is part of it... the main issue jrreeve is pointing out (please excuse me if I am wrong about your position jr) is something called unsprung weight.

Unsprung weight is a term used to describe that part of a vehicle's mass that is directly connected to the wheels, and not isolated through the suspension. Unsprung weights typically consists of the weight of the wheels, tires, brakes, half-shafts & the suspension pieces themselves.

Because this part of a vehicle is in direct connection to the road and therefore subject to all of its imperfections, it is important that this weight be as low as possible, or at least much lower than the weight of the sprung part of the vehicle, in order that the wheels maintain optimal contact with the road surface. The greater the unsprung weight, the greater the inertia of the suspension, which will be unable to respond as quickly to rapid changes at the interface between the road and wheel. Unsprung weight can be reduced by using light alloy wheels, independent rear suspension on rear and all wheel drive vehicles (where the weight of the rear differential is not part of the unsprung weight), and front-wheel drive.

The classic design of rear-wheel drive through a live axle gives quite a high unsprung weight, which is one reason why it has fallen out of favour.

The basic balance is between the ability of the suspension system to supply reactive forces to the mass of the unsprung weight in order to counteract the forces supplied by road surface imperfections. Heavy unsprung weight can overload a suspension systems ability to react, leading to tire hop, slapping, poor traction & bad ride and handling.

So, what does all this mean to the average transaxle owner when selecting a new set of rims? Not much in my opinion. Go for what looks nice to you and fits properly.

Cheers,

-Brian
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Wheels

Post by hutchensgd » Sat Jan 01, 2005 6:36 pm

Thanks for the information. I have learned a lot about cars from you guys thanks.

What do you think is the tangible difference between 16 and 17 inch tires / wheels. Assume same rims, tires.
Glenn
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Post by ar4me » Sat Jan 01, 2005 8:14 pm

So, what does all this mean to the average transaxle owner when selecting a new set of rims? Not much in my opinion. Go for what looks nice to you and fits properly.
Hmm, I would add some granularity: Pick the superior solution from a technical stand point if performance matters most to you, or pick the aesthetic superior solution if that matters most to you. Being an engineer I would opt for the light wheel, but still look long for a pleasing looking wheel ;-)

Personally, even if it is marginal I prefer the technical "correct" solution... not always practical :roll:

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Post by Zamani » Sat Jan 01, 2005 11:00 pm

I'm using 225/50/16 race tires on my 75. The fender needs to be wokred a little (just the inner lip), the bumper needs to be shifted forward a little and the rear section of the front wheel well needs to be worked on a little.

I prefer lighter wheels. On a TV program here they showed results where bigger disc brakes resulted in lower wheel bhp (not by much). It was on an Acura RSX (K20A iVTEC) and they lost 5 wheel bhp.

Anything above 18 lbs is heavy in my book. About 17 lbs is acceptable. The Team Dynamics Pro Race 1 is a good choice. It looks good, not too expensive and weight is low.
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Post by 4SFED4 » Sun Jan 02, 2005 7:23 am

Glenn,

For the street... no tangible difference.

235/40 17 or 245/45 16 is as wide/big as you can go without fender well modifications on a 116 chassis. I am not sure about the 161 chassis. I should also note the front spoiler on the GTV6 reduces the amount of clearance at the front of the wheel well.

Are you familiar with www.1010tires.com ?

They have a nice tire size calculator and you can view wheels on YOUR very own car! Look for the "Custom Car Wizard" under the wheels section, it is pretty cool.

-Brian
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Thanks!

Post by hutchensgd » Sun Jan 02, 2005 8:03 am

Brian,

I was not aware of that resource, but I appreciate you letting me know about it. I was totally utilizing the recomendations of Ronal USA for this.

Thanks again,

Glenn
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Post by Mats » Sun Jan 02, 2005 3:40 pm

Adding another level on the unsprung weight issue...

Inertia.
Making the wheels bigger will almost always make them more difficult to accelerate. Think of it as flywheels, the heavier they are the more energy you need to put into it to get it up to a certain speed and that energy needs to be taken out of it to stop it.
So not only will it steal engine power it will make your brakes work harder. Thats bad.
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