Couldn't find anything, I swear!!

[Francesco]

Sorry in advance ,
I know this question has been asked about a billion times, but I've never found an exact answer. Let's say I'm going to run STOCK suspension, with HD coils and the 2 inch drop S10 spindles in the front(do these change the backspacing at all? also the ones modified by levair). I was told this changes the BS needed by 3/8"??? What would be the perfect backspacing for a 15x7 rim?? I know people say 4-5", but what is the best? Do I just cut it down the middle and go 4.5? I hear 4 rubs, and then I hear is doesn't rub, then the same with 5, then I hear about one guy running 3.5" BS and he has no issues. I don't know what to think or believe, but I want to get a set of new minilites made for my car, and I want them to fit!!!!! I want to be able to hit bump stops while flying into a corner (not saying I'm going to do this) and have no tire rub, wheels locked in either direction. I plan on running a 205/60/15 in the front (or the corresponding 14" size), and a 225/50/15 in the rear(same as before). I also am worried about the 15" tire availability. Would 14s be easier to find tires for? I have seen a few threads about that, however they're all like 4-5 years old. Also, on the autoxer site, it says you can fit a 235/14, but only a 225/15?? All of this confuses me, I don't think the wheel well knows what size the rim is! What I'm asking basically is the PERFECT backspacing, with a disc brake conversion in the front!(if I convert rear, will the BS change using corvair underground's kit?) I hope I don't make too many people mad with this post, haha! Thank you for any help I get, and hopefully this post will help some other people in the same boat as me as well.

[66vairguy]

Wow - you just opened a can of worms and why I try to avoid modifying suspension.

The tire center contact point with the road is aligned with a "centerline" based on the suspension points, the ball joints or king pins, etc. Basically the further the center of the tire is from the geometric pivot point the more the tire "scrubs". Some scrub can be desirable, depending on the suspension. Bottom line - the engineers spent a LOT of time getting the car to handle and steer well. Yes technology has advanced since the mid 60's, but don't poo poo the Corvair front suspension, even today it works well. Then there is the quandary - do you want to deal with street roads, or go racing?

Make the car tire/wheel diameter bigger and your off the factory centerline. Drop the spindle center and your off the factory centerline.

Unless you did well in college taking a geometry class and read up on automotive suspension geometry, then trying to figure out what works is going to be daunting. You'll probably end up relying on others to know what they are doing. My experience is that doesn't always work out so I try to stay close to the stock setup. Increase the rim width by half an inch, then increase the back space by half that, but keep the tire circumference close to stock (825 - 845 revolutions per mile), etc. Just me!

[Francesco]

Thank you for commenting. I don't plan on going too much different than stock on tire size, I just would like bigger wheels (tire availability), as well as discs. I guess I need some opinions. Has anyone done the S10 swap? How did it affect your steering geometry?

[bbodie52]

As for obtaining tire specifications with charts that cover a wide range of tire brands, I have found the Tire Rack website to be very informative.

http://www.tirerack.com/content/tirerac ... epage.html

Their data won't necessarily cover the Corvair specifically, but if you have known tire sizing that works for a late or early model Corvair (front or rear) and you know the desired overall diameter, revs per mile, etc. for use on your car, you can examine tires in almost any performance category, speed range, etc. to check on availability, and what similar tires will fit if you change rim diameter. Acceptable wheel widths for a given tire size is also provided on the charts, and consumer performance evaluations and feedback is also provided. Consulting with a Tire Rack technical adviser on the phone can also help to clarify things. The combination of Corvair-specific knowledge and sizing advice on the Internet and current tire market information from suppliers like Tire Rack can help you to obtain a great deal of technical tire and wheel fitment information as you work to "desktop" your best informed sizing data. Modifying the car to include unique variables such as changing to front and rear disc brakes can take you into the realm of the unknown, or experimental modifications wherein your best educated guess may lead to a successful outcome or to an unintended negative consequence. Sometimes going a little-more conservative in your final tire size selection might help, since trying to insert the widest-possible tires and wheels into the confines of the Corvair wheel well can lead to problems.

[Francesco]

I don't plan on going ridiculous, I was told 205/60-15 was about the same as stock! In the rears, I'd like a 225/50-15, just to lower my freeway RPMs and have a little bit more meat. According to most I've read, that's not pushing the boundaries. I just want to know if le vair's kit changes backspacing, and if so by how much, and since I get to choose my backspacing with custom wheels, what is the right backspacing to get the wheels cut at?

[Francesco]

Hi, I'm back again. I plan on ordering a set of Minilite wheels in 15x7 and 15x8. Since they will be new, I get to pick the backspacing. I plan on 205/60-15, and 225/50-15. I don't want it to rub, no matter what! What would be the PERFECT backspacing?

[66vairguy]

Hi, I'm back again. I plan on ordering a set of Minilite wheels in 15x7 and 15x8. Since they will be new, I get to pick the backspacing. I plan on 205/60-15, and 225/50-15. I don't want it to rub, no matter what! What would be the PERFECT backspacing?

Well ---- I can't calculate that for you, but one thing to keep in mind - you can only move the rim so far inward before you have clearance issues. The factory back space was 4.25" and that should have allowed for the use of tire chains in the snow. So going to a 4.50 backspace, and assuming the tire circumference is close to stock, should not be an issue. That said - stock rim width was 5.5 " with a 4.25" backspace. So a six inch wide rim with a 4.5" backspace is the same. Running a 7" wide rim and now you are increasing tire scrub radius in a turn. Not a whole lot and in the 60's folks ran "deep" rims with less backspace than stock with custom rims that "looked" better in the wheel well without a lot of issues. Anyway --- for normal driving probably fine. BTW = A 205/70X14" looks better on a 6" wide rim, but a lower profile tire can require a wider rim. Go with what the tire manufacturer says - Tire Rack usually states the rim width for a tire.