Max Wheel Offset for a Spider

[msiert]

I have decided that it's time to buy a set of deducated track wheels for my Spider. For the last year I have been using my Kumho Ecsta700 for the street and track events.

I found some wheels that were made for the Ford Escort they have the correct bolt pattern but their offset is 35 mm. I will be running the Kumho's that are 205/50/15 on them will that offset work?

If I buy these wheels I will need to buy a set of street tires to replace the Kumho's that I used for the street. Can I go to a wider tire in the rear? I would go with the 205/55/15 on the front and 215/55/15 in the rear? I have 15 x 7 Panasports. I have heard if you don't have ABS brakes you can go to wider tires in the rear. I will have to check but I don't think a S-4 Spider has ABS Brakes if they do I never felt them?

Any help would be great.

Murray

[JoeCab]

A couple of points:

1) With a 7" wide wheel, I think an offset of ET25-30 would be better than ET35 for offset.

2) You could go a wider wheel in back - the Spiders never had ABS. It may rub on the innner fender liner. But, the bigger question is why would you need to? Is straight line traction a problem? - It rarely is on Alfas. Also, a wider tire in the rear would probably add a fair bit of understeer. So, if you're going for the wide look in back, go ahead, but it probably won't add anything to the driving experience.

Joe

[genericwood]

Murray, if the wheels with 35mm offset don't work, just use wheel spacers. Those wheels with a 1/4 inch spacer are like having a 29mm offset. With a 1/2 inch spacer its more like 22-23 mm. If you anticipate having clearance problems, it is probably best to have too much offset. Then you can fine-tune with wheel spacers.

Erik

Quote:

Originally Posted by msiert If I go down to a 15x6 wheel will the 35 mm offset work? Your right no reason to go wider plus all the tires I am look at jump from 205 to 225. Thank you, Murray

[conedriver]

Hi Murray,

Before considering different size tires, be sure you know the overall dimensions. Do a search for "Tire Size Calculators" on the web; one of these will allow you to compare tire diameters, which will affect your overall gearing. Also, check the tire manufacturers sites for recommended rim size (or use the excellent Tire Rack site). A 6.00 rim sounds too narrow for a 225 section tire. I use 225/45x15 Hoosiers on a 8.50 wide rim, however, I cut the wheel openings to provide clearance.

My 8.50 wheels have a 4.25 in. backspace, placing the inside of the rim in the same location as a stock wheel. With a 22.90 overall diameter, the outside edge of the tire rubs on the back of the front wheel well with the steering at full lock. I also use 1/4 in. spacers at the back to eliminate a slight rub on the inside of the wheel well.

And... check your owners manual, S4 spiders do NOT have ABS.

Quote:

Originally Posted by msiert If I go down to a 15x6 wheel will the 35 mm offset work? Your right no reason to go wider plus all the tires I am look at jump from 205 to 225. Thank you, Murray

[conedriver]

Murray,

I knew the phone dial wheels were heavy, but didn't know the exact weight. For a track wheel, search the various autocross sites like http://www.midatlanticmotorsport.com/ or http://www.tirerack.com/ , they have lots of lightweight wheels. Or, try Centerline "Autodrag" like I use. These are around 13 lb. each and were $125.00 each several years ago. Kinda ugly, but a good deal.

Light weight wheels really make a difference. A racing friend once told me "a car has five flywheels, one on the engine and one on each corner of the car, and they all affect the rate of acceleration". I wonder how much performance penalty people pay for the 17, 18 & 20 in. diameter wheels they use for "stylish" enhancement?.

Quote:

Originally Posted by msiert Hi George, Went to school last night. But now I understand what to look for in offsets. The problem was I was looking at wheels with positive offsets. Recently purchase some 15 x 7 Panasports which I like to use for the street sense this is what the main use of the car is. I still have the old 15 x 6 Phone Dials that I could use as my track wheels for the two track events I go to in the summer but they weigh in at 26.5 Lbs. I want to buy a cheap set of light weight track wheels to put my 205/50/15 Ecsta's on and buy a set of street tires for the Panasports. The idea of wider tires on the back was not a good one and has gone by the way side. Thanks for your reply, Murray

[genericwood]

Murray, the 4 x 4 1/4 is the bolt spacing you need. It is only .050" off of a 4x108mm. In other words, they are interchangeable. If you have determined that you need 25-30mm offset, then you may not want as much as 4 7/8" backspacing. That backspacing works out to more like 35mm of offset. With zero offset, a 7" wheel would have 3.5" to the outside of the hub face and 3.5" to the inside. The difference between the 2 values (4 7/8" and 3 1/2") is your offset. In this case it is 1 3/8" or about 34.9mm. If the backspacing was measured all the way to the outside lip instead of the bead seat, then the offset is probably a little less. Either way, as I mentioned yesterday, you can always use a 1/4" (or larger) spacer to gain clearance on the inside!

Erik

[genericwood]

Murray, I may have positive and negative offset reversed. But just about everything you might consider has the offset the direction you want! You want more of the wheel to the inside of the hub center. Front drivers are all offset in this direction, but often more so than you want with your Spider.

As to maximizing the track in the rear, technically the wider the track the better for handling. But there are lots of caviats. I would just space the wheels as needed for the best appearance and least chance of rubbing.

Erik