I am looking at wheels. I see people putting 19" on back and 18" in front. And, I see 18" in back and 17" in front.

When I think of it logically if I use a larger diameter wheel in back I am going to have to go down on the profile of tire to keep the speedo accurate. So, yes I will have a larger looking wheel in back, but a noticeably less meaty tire on the wheel. Strikes me it would look funky.

What is this accomplishing exactly? Help me understand.

first off its all about the look. my 92 vette has 17 fronts and 18 rears. but isnt the speedo read off of the front tires?

No, the speedo is read from the transmission. In my case, geared for 15" wheels with 215/60/15 tires.

As far as "the look". In the pics I have seen I must not have been looking closely enough. I couldn't even tell they were different.

Most of the ones I have seen match the tires so the same amount of "meat" is on all four. So, the back tire will be about an inch taller. The only problem with this setup is cars with ABS and 4X4's.

So what do you do? Make the back tire diameter match the original diameter and get the tires in the front to match that profile? This should make the speedo correct and give the desired effect.

Anyone have a pic that really demonstrates the impact on appearance from using staggered wheel sizes?

Yeah, if the back tire is close to the factory size, the speedo will be close. Then the front tire will be about an inch shorter in diameter if the profile is the same.
Most places use the term staggered when talking about wheels with the same diameter front and back, but different widths. (88 Fiero GT, Formula)
The Corvette is a good example of the setup you are wanting.

The Corvette is beautiful. The wheels look great. However, it is difficult to see the wheels size difference and their effects. Got another shot dead on from the side?

Thx for the help.

Here are two tire/wheel calculators to help you calculate your speedometer reading with your choice of wheels and tires. This will help save you from a speeding ticket. I'm sure that you've seen these before, just plug in your proposed tire wheel sizes, easy enough.

http://www.miata.net/garage/tirecalc.html

http://www.venommotorsports...ewheelcalculator.asp

I didn't have staggered wheels but I did stagger the tire sizes on my old 87 GT, 215 front and 235 in back for a nice graceful rake.

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It's no different than running wider tires in the rear than the front in the sense that you're going to have to run two different profiles. The inside wheel size (third number) doesn't really make much difference.

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my vette has 17 inch fronts and 18 inch rears

The practice of putting larger diameter wheels in the rear or smaller diameter wheels in the front is purely aesthetic.

The Infiniti G35 Coupe has a larger diameter wheel in the rear and as a result, you cannot rotate your tires. This coupled with a lot of negative camber and soft compound tires equals tire changes every 15-20,000 miles, depending on driving style. (In the short time I worked there, I actually had one customer come in for his 3,500 mile (very first) oil change and the inboard half of both rear tires was at 2/32" tread depth.)

I would not recommend different wheel sizes to anyone with a "Check Wallet Light". ( <--- credit to Jetman for that one, hehe.)
I've no issue with stepping up to a larger diameter wheel so long as they're the same size. The larger the wheel and lower profile the tire, the more of the road you can feel and the less "tire roll" you'll experience in the twists. That equals a bit rougher ride, but a lot more control and predictability.

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Larger tires in the rear isn't always purely aesthetic. The larger tire gives added traction over a smaller tire. A larger rear tire raises the ride height of the rear of the car, and in some automobiles, improves handling. Personally, I think that's the reason Pontiac went to the staggered front and rear tires. I believe with the additional 200 lbs of the fastback over the notchie, it was a move to reduce the understeer.

If the rear is set higher, it will tend to come around better in hard turns. I have a notchie that I installed staggered sizes onto, and I went with 215's up front and 245's on the rear. It handles much much better than it did with the original 14's all around. I've had no problems with understeer.

I'd say that there are three reasons for using staggered tires:
1. The look.
2. On a front-heavy car, meaty rear tires to avoid oversteer causing lawsuits from incompetent drivers.
3. Non 50-50 weight distribution.

The lateral force a tire can produce is not directly proportional to the normal force.

Therefore, with equally sized tires, but uneven weight distribution, you can have different coefficients of friction, and hence oversteer or understeer depending on your situation.

So ideally, you want to have the meaty tires at the heavy end, and the skinny ones at the lighter end of the car, so that all tires are operating at the same coefficient of friction.

While it may work for performance, something I always chuckle at are the ricer guys with big tires on the front (drive wheels) and little dinky ones on the back since they just hold the car up. What gets me to really belly laugh though is the ricer guys (still FWD) that put big tires on the back and little ones up front....of course it makes squeeling tires simple for 100 hp. Taking off unloads the front, and tiny ones spin nice if your putting on a show for girls walking down the sidewalk.

quote Originally posted by Brocephus: The practice of putting larger diameter wheels in the rear or smaller diameter wheels in the front is purely aesthetic.

No that is not accurate. It all depends on the chassis layout.
Quote from Herb Adams:
The basic handling problems any rear- or mid-engine car is that the center of gravity is behind the traction center of the tires.  Rear-engine race cars compensate for this by using larger tires on the back and smaller tires on the front.  This moves the traction center to the rear so it is on, or behind, the center of gravity.  You can use larger rear tires on your Fiero for the same benefit.  The stock rear fenders have room for 255/50x16 tires on 16x9 wheels, although 225/50x16 tires on 16x8 wheels will also provide improvement.

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Now if we're talking about different diameters, rather than just staggered widths, well that opens up a whole new can of worms.

That's also going to change the brake bias.
A noticeable amount? I don't know, I'm not a racecar driver.
I'm just trying to make people aware that different diameters will affect this.

But in the case of the Fiero, with the brakes too front-biased already, smaller diameter front than rear tires can only increase stopping distance.

The brake bias issue is compounded because the same people who have the 18/19" huge rims are usually also lowered, reducing weight transfer to the front on braking.

quote Originally posted by sjmaye: I am looking at wheels. I see people putting 19" on back and 18" in front. And, I see 18" in back and 17" in front. When I think of it logically if I use a larger diameter wheel in back I am going to have to go down on the profile of tire to keep the speedo accurate. So, yes I will have a larger looking wheel in back, but a noticeably less meaty tire on the wheel. Strikes me it would look funky. What is this accomplishing exactly? Help me understand.

There are some preformance benifits which have been listed but as far as seeing a difference, Its not what you see but what you dont see.
If you look at a Fiero with staggered rims with appropriate tires, It looks correct or OEM.
If you look at a Fiero without staggered rims, The rear tire seems to sit a little lower than it should and the rim appears a bit smaller even though they are the same size.

Its basically an optical illusion. Just my opinion.

Steve

quote Originally posted by JumpStart: There are some preformance benifits which have been listed but as far as seeing a difference, Its not what you see but what you dont see. If you look at a Fiero with staggered rims with appropriate tires, It looks correct or OEM. If you look at a Fiero without staggered rims, The rear tire seems to sit a little lower than it should and the rim appears a bit smaller even though they are the same size. Its basically an optical illusion. Just my opinion. Steve

I would tend to agree with this assessment. I have two Fieros. I just put a set of 18"x8" wheels on my 87. Looking from the side it looks good, but the rear somehow looks a hair smaller. It is probably as you say, a result of the wheel against the wheel opening.

The wheels I am looking at for the 88 are not available below 18, so I am looking at 18 and 19's. I hate the though of the super low profile I will need on a 19" wheel to have the speedo accurate. Sure wish there was a gear I could change or something so I could use a slightly higher profile. The bumps would also be easier on my old back.

One thing you can do on a manual tranny is drop to a 29 tooth vss gear. This will increase the speed of the signal to the speedometer. Though it may not be completly accurate, it will bring you up closer to your true speed.

In my case, I went from stock 14's to 245/60/15's on the rear with a stock 30 tooth vss gear. When my speedometer was indicating 60, I was actually somewhere over 70. It was reading much slower. I didn't realize this until I noticed that when I was running 70, I was passing everything on the interstate. I checked it against the mile markers and I was one and a half to 2 tenths mile off. I installed the 29 tooth gear and I'm averaging .08 to .10 miles off as measured against the mile markers. So, I just calculate in my mind that I'm 10 % off. Hense, add 5 mph at 50, 6 mph at 60, etc.

I don't know if there are different vss gears for the automatics, but it would seem that an 84 with 13 inch wheels would have a different gear than an 88 with 15's.

quote Originally posted by Brocephus: The practice of putting larger diameter wheels in the rear or smaller diameter wheels in the front is purely aesthetic. The Infiniti G35 Coupe has a larger diameter wheel in the rear and as a result, you cannot rotate your tires. This coupled with a lot of negative camber and soft compound tires equals tire changes every 15-20,000 miles, depending on driving style. (In the short time I worked there, I actually had one customer come in for his 3,500 mile (very first) oil change and the inboard half of both rear tires was at 2/32" tread depth.) I would not recommend different wheel sizes to anyone with a "Check Wallet Light". ( <--- credit to Jetman for that one, hehe.) I've no issue with stepping up to a larger diameter wheel so long as they're the same size. The larger the wheel and lower profile the tire, the more of the road you can feel and the less "tire roll" you'll experience in the twists. That equals a bit rougher ride, but a lot more control and predictability.

What this means to me is you just end up replacing two tires at a team twice as often instead of four at the regular rate.

I was just reviewing the post that got me looking at staggered wheel sizes in the first place. I looked more closely at the pic. I do see the difference. These are 19 and 18. Tread height doesn't look bad at all. I am now looking at a set just like these or maybe the split 5.0's.

quote Originally posted by sjmaye: So what do you do? Make the back tire diameter match the original diameter and get the tires in the front to match that profile? This should make the speedo correct and give the desired effect. Anyone have a pic that really demonstrates the impact on appearance from using staggered wheel sizes?

The black Z06 is mine but the yellow one I had in my file. You can see profile appearance in these shots. They look 10 X better in person, in fact,
when I gas up I walk around the car and look at the tire size differance. My Z06 has the fattest back tire I have ever seen in person ! ! !
Front Tire : 275/35ZR/18 Rear Tire : 325/30ZR/19

[This message has been edited by NOLUCK13 (edited 02-21-2009).]