Well, I have an 1988 Coupe with aftermarket 15" american racing wheels, I have 205/60/15 on the front, should I go 215/60/15 on the rear or the same size as the front? I know the Formula's and GT's have a little bigger in the back... would it handle better the same all the way around?? Please help! Dave
------------------ DAVE'S 1988 FIERO COUPE ( 5 SPEED SHORT SHIFTER - GT DUAL EXHAUST )
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08:48 AM
PFF
System Bot
jsmorter1 Member
Posts: 674 From: Creston, Ohio Registered: Jun 2004
You have 205s on a six inch rim- I would go with 225/60/15 on the rears since it is a seven inch rim. You also have more weight in the back so a wider tire is needed to have the same control in the back that you do in the front assuming all else is equal. With the 225s your speedometer will be off a little. It will read about 2 percect less than you are actually going.
------------------ I am sick and tired of being sick and tired Virgin 88 coupe in the process of losing its virginity
It's a coupe, it doesn't have staggered rim sizes.
See thats what I thought, but it does have aftermarket 15" american racing wheels, the stock ones were 14" correct?? I am actually not sure, I bought the car like this. Dave
------------------ DAVE'S 1988 FIERO COUPE ( 5 SPEED SHORT SHIFTER - GT DUAL EXHAUST )
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02:33 PM
jsmorter1 Member
Posts: 674 From: Creston, Ohio Registered: Jun 2004
my mistake I thought he meant formula type 15 inch wheels. basically you fit the tire to the size rim you have. you do have some leeway as far as going with approved tire sizes for the rim width but you are looking at different handling characteristics if you compare a 205 on a 7 inch rim to a 225 on a seven inch rim
Your car originally came with all 4 wheels the same with 185/75/14 tires because it was a 4 cylinder car.
The 1988 Fiero got a entirely new redesigned suspension in it's final year of production with a wider front suspension. When running larger wheels & tires they need to be "staggered" just like on european exotic cars.
The GT and Formula V6 models had different sizes...
Most likely the American Racing aftermarket rims your car came with are 15x6 or 15x7, with all 4 the same size and the same offsets. If you plan on keeping those wheels, I would use 205/60/15 on all 4 corners if that is the case.
If you want bigger wheels or tires, your going to have to get different staggered aftermarket rims.
Or you could buy a set of factory wheels you car originally came with.
Another option... You could also buy a set of used 1988 GT rims, that would give you the proper staggered setup with larger tires.
[This message has been edited by Skybax (edited 03-27-2005).]
any 88 with four of the same wheels, will have the fronts sticking out a bit more. The best thing to do for best handeling and looks, get the fattest tire you can fit on the rear!
you will be unhappy if you get all the same size, trust that.
[This message has been edited by zMacK (edited 03-27-2005).]
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05:29 PM
LT-5Fiero Member
Posts: 336 From: Charlotte, NC Registered: Oct 2002
any 88 with four of the same wheels, will have the fronts sticking out a bit more. The best thing to do for best handeling and looks, get the fattest tire you can fit on the rear!
you will be unhappy if you get all the same size, trust that.
The mind is a powerful thing, but so easily fooled. When you go with a wider tire, you change the optimal slip angle of the tire. Allowing the tire to slip at a more shallow angle to get its peak amount of grip. The decreased slip angle means less total slippage and thus reducing tire temperature, not to mention more rubber to distribute that heat across.
Look at this with blinders, wider is better, but why keep all the wideness to the rear?
Having two different slip angles for the front and rear tires creates a handling problem. Your not curing understeer or oversteer, but rather making an illusion of it. If you run a staggered setup and find all tires slipping at the same angle, then either your front or rear tires are outside of their optimal slip angle.
Sport Compact Car in a recent issue make this known to the public when they tuned the suspension of a 350Z for appropriate weight distribution, appropriate downforce, appropriate spring rates and ditching the factory staggered tire setup. When finished, they achieved a car that was 1 MPH faster through the slalom than Nissan's factory Track Package and 1.6 MPH faster than Nissan's standard 350Z and bumped up to 1.0g on the skidpad both ways.
------------------ Soon to possess: (1) 87 black GT with 77,000 miles and a hole in the block
Originally posted by LT-5Fiero: Sport Compact Car in a recent issue make this known to the public when they tuned the suspension of a 350Z for appropriate weight distribution, appropriate downforce, appropriate spring rates and ditching the factory staggered tire setup. When finished, they achieved a car that was 1 MPH faster through the slalom than Nissan's factory Track Package and 1.6 MPH faster than Nissan's standard 350Z and bumped up to 1.0g on the skidpad both ways.
All this with a car that is dissimilar to the Fiero, "apples and oranges" so to speak. You can get close to 50/50 weight distribution in a Fiero, but you have to move stuff and lose stuff or put in an aluminum block & head four cyl. power-plant. In the 350ZX they started w/ the wide tires on the light end, as opposed to the Fiero's heavy end. And I have heard that a properly tuned Fiero raises the ante on that 1.0G. Norm
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02:42 AM
LT-5Fiero Member
Posts: 336 From: Charlotte, NC Registered: Oct 2002
All this with a car that is dissimilar to the Fiero, "apples and oranges" so to speak. You can get close to 50/50 weight distribution in a Fiero, but you have to move stuff and lose stuff or put in an aluminum block & head four cyl. power-plant. In the 350ZX they started w/ the wide tires on the light end, as opposed to the Fiero's heavy end. And I have heard that a properly tuned Fiero raises the ante on that 1.0G. Norm
What they did to that 350Z (Which BTW has a 53/47 distribution from the factory) is what you would do to most any car, from SAE to SCCA SoloII. There is always room for improvement and just because someone had some luck in running obscenely wider tires in the rear than the front of the Fiero, does not mean that is the way to do it. I gave you the science behind it all, having tires with two different slip angles at opposite ends of the vehicle is a bad thing, unless you drift your Fiero. You cannot refute that.
------------------ Soon to possess: (1) 87 black GT with 77,000 miles and a hole in the block
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11:00 AM
Will Member
Posts: 14300 From: Where you least expect me Registered: Jun 2000
Originally posted by LT-5Fiero: Look at this with blinders, wider is better, but why keep all the wideness to the rear?
Having two different slip angles for the front and rear tires creates a handling problem. Your not curing understeer or oversteer, but rather making an illusion of it. If you run a staggered setup and find all tires slipping at the same angle, then either your front or rear tires are outside of their optimal slip angle.
You're looking with blinders. Your analysis of slip angles neglects to figure in the greater weight the back tires have to deal with. To generate a given cornering G in a Fiero, the rear tires must create more lateral force than the front tires. If the car is running the same tires all around, then the rears will have a greater slip angle than the fronts and run out of traction before the fronts do... a classic Fiero handling problem. The solution is to increase the width of the rear tires until they are operating at the same slip angle as the fronts. This happens when the front/rear tire distribution matches the front/rear weight distribution. IE with a 45/55 weight dist, the front tires should have 80% of the width of the rear tires (45/55 ~ 0.8). This is EXACTLY what the SCC article shows, although it's less clear in that article since they used a car with 50/50 weight dist.
quote
Sport Compact Car in a recent issue make this known to the public when they tuned the suspension of a 350Z for appropriate weight distribution, appropriate downforce, appropriate spring rates and ditching the factory staggered tire setup. When finished, they achieved a car that was 1 MPH faster through the slalom than Nissan's factory Track Package and 1.6 MPH faster than Nissan's standard 350Z and bumped up to 1.0g on the skidpad both ways.
Which SCC issue is that? The 350Z is dam near 50/50... it DOES need the same size tires all around. Nissan probably staggered the tires to give it safe understeer... Anyone who does that in the aftermarket is a fool.
Originally posted by LT-5Fiero: There is always room for improvement and just because someone had some luck in running obscenely wider tires in the rear than the front of the Fiero, does not mean that is the way to do it. I gave you the science behind it all, having tires with two different slip angles at opposite ends of the vehicle is a bad thing, unless you drift your Fiero. You cannot refute that.
The tires on the rear of the stock Fiero are not obscenely wider than than the front! They match the weight differential. You showed us science? Man these must be toilet-paper tubes I'm looking through not merely blinders. Go buy a book. .. Start here ... 'How to make your car handle' I don't have it @ my fingertips right now, but the author I believe is Greg Puhn. You might have to brush up on your math skills though. I've past the mid-century mark, have had a few hobbies, and look at magazine articles with a somewhat jaded eye, too many generalizations to fit the broader spectrum of enthusiasts. Not to mention bias towards their advertising base. Just because someone had the cajones to put something in B/W in a 'hobby rag' doesn't mean he put the same energy he put into his (or her) masters thesis.Just exactly who's money were they playing with anyway? Perhaps wider tires in the front could improve the on the skid-pad #s even more, bet the styling gurus would love that. They'd probably have to put '88 front wheel bearings and a super high offset on it though. ;^) Norm
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01:26 PM
LT-5Fiero Member
Posts: 336 From: Charlotte, NC Registered: Oct 2002
The Fiero is a far more neutral car than my daily driver is, with a 60/40 distribution, with it being FWD and 245/40R17s on the front, someone help me with my fledging math skills here. So I should run something in the 175 to 185 range on the rear?
I am always up for a challenge though and man enough for someone who is 30 years away from his mid-century mark to admit when he is wrong and defeated. My Fiero will be running around the track with the same size rubbers front and rear and we will see who is wrong.
Now back to your reguraly scheduled programming.
------------------ Soon to possess: (1) 87 black GT with 77,000 miles and a hole in the block
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03:05 PM
doublec4 Member
Posts: 8289 From: Oakville, Ontario, Canada Registered: Jun 2003
...My Fiero will be running around the track with the same size rubbers front and rear and we will see who is wrong.
...but your traction is not strictly limited to your tires - unless you're specifically doing a spec comparison where both cars have identical suspensions (in which case tyre compound and tread pattern may even have a greater affect on the handling - also something noted from a recent SCC article ).
Also, last year's "wheatstock" driving event at Heartland Park in Topeka Kansas proved that conditions can have an even greater affect (as proved by Racingman24's underpowered 4-banger outperforming most of the higher powered cars by simply being able to press the gas without worry of traction loss in the wet).
I think what I am going too do is go with these for the rears Falken Ziex ZE-512 215/60R15 I have the same ones on the front that are 205/60R15 Figure that would match the best?? Cost is a factor seeing I dont wanna spend 100 a tire. Dave
Ps...I have read all this input and it is really interesting.
------------------ DAVE'S 1988 FIERO COUPE ( 5 SPEED SHORT SHIFTER - GT DUAL EXHAUST )
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04:36 PM
LT-5Fiero Member
Posts: 336 From: Charlotte, NC Registered: Oct 2002
California Kid has some impressive skid pad numbers on his 88. Find out what he acheived them with?
215/50R16 and 245/50R16 BFG Radial Comp T/As, yes I know and 215 is 87% of the width of 245, not 80%. He would of probably felt quite silly wearing 195s on the front of his Viper Yellow Fiero.
He probably could of also found an increase in wheel width being beneficial to him as well. Yet that is more bantering from this youngin' for another discussion at another time.
I agree wholeheartedly Minn, compounds, conditions, applications, they all vary and create different results, and not what will work for one car will work for the other, yet there are many generally held rules that apply to all. Such as, go lighter, go faster, the same is true for neutral or near-neutral cars like the RX7, 350Z and Fiero, you don't dumb it down with staggered tires.
[This message has been edited by LT-5Fiero (edited 03-28-2005).]
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05:16 PM
Will Member
Posts: 14300 From: Where you least expect me Registered: Jun 2000
I don't know where you're getting that the Fiero is neutral with equal tires, but it is NOT, especially once you start trying to tune the suspension...
Two fieros ive had were identical except tires... New shocks, pre 88 setup... first one had 215/60-16 on all four tires the one I have now has 245/50-16 on the back, 215/60-16 on the front The fatter tires on the back give me way better feel. I just know. Ive had 16s on my other fiero too, they were slightly less staggered but still not the same. all good quality tires
Im working off what ive experianced here. Not trying to slam you but fieros DO like bigger rear tires, nomatter what the setup all three had stock tech wheels
Ya, i have bought way too many rims/tires for fieros lol
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08:11 PM
DAVES85GT Member
Posts: 697 From: North Tonawanda N.Y. USA Registered: Aug 2001
I was wondering if I could go 225/60/15 in the rear then, I have to keep the 205/60/15 in the front since thier new. OR should I just go 215/60/15 in the rear slightly bigger? thats whats on the car now and it handles pretty good. Dave
------------------ DAVE'S 1988 FIERO COUPE ( 5 SPEED SHORT SHIFTER - GT DUAL EXHAUST )
If you want to start playing with larger size tires you are going to need to first find out what width those aftermarket rims are and what the offset is.
It's much easier to choose tires when you know what the rim specs are.
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10:35 PM
PFF
System Bot
DAVES85GT Member
Posts: 697 From: North Tonawanda N.Y. USA Registered: Aug 2001
Well, I know thier is 215/60/15 in the rear right now, and 205/60/15 on the front so maybee I will just replace the rears with the same size thats on thier now. since the fronts are like new.... Might as well stick with whats on thier and whats works? right???
------------------ DAVE'S 1988 FIERO COUPE ( 5 SPEED SHORT SHIFTER - GT DUAL EXHAUST )
You have 205s on a six inch rim- I would go with 225/60/15 on the rears since it is a seven inch rim. You also have more weight in the back so a wider tire is needed to have the same control in the back that you do in the front assuming all else is equal. With the 225s your speedometer will be off a little. It will read about 2 percect less than you are actually going.
Really? I'm currently running 225ZR16's in the back (and on the front, too) on my 87' GT and my speedo seems normal, though I may just not notice the diff...
------------------ Chris
Blue 1987 GT Getrag 5 speed, 1" lowering springs, 225 50R16 rims and tires, Fiero Store 9 3/4" HD clutch (Halfway through a 3.4L TDC Swap! Build Thread: [URL=https://www.fiero.nl/forum/Forum2/HTML/059801.html[/URL]) Silver 1986 2m4 THM 125c automatic (Current commuter) Black 1985 2m4 SE Isuzu 5 speed (no paperwork)
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