I bought 17" rims for my car. They're 7 inches wide. I got 235/45/17 for the back because I would rather have my odometer read slightly low than slightly high (plus, wide tires are cool). The problem that I have is what to get on the front. With stock sizing, the front tires (205/60/15) are 10MM thinner than the rears (215/60/15). I have not bought front tires yet because I am not sure how to do this.

Here is the question:
Should I get 215/45/17 for the front? This would keep the fronts approximately the same diameter.

Or...

Should I get 225/45/17 for the front? This would keep the same 10MM difference between front and rear.

Thanks,
Steve

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87 GT Auto: 2.25" Goerlich XLerator exhaust, high-flow cat, NGK plugs, KN Filter, Black Carpet, FieroWarehouse Gen2 Side scoop
AIM: derangedsheep | email: elcodjsteveo@yahoo.com | CarDomain | Fiero Presentation
~In Memory of Lorena Fuller (27Jan88 - 15Nov04) and Jason Dubble (21Jun87 - 01Apr05)~

[This message has been edited by derangedsheep (edited 06-07-2005).]

i say go 225. I got 225/45/17 on my wheels...it's always better to have more grip on the road. Let's not forget, the tires are essentially the most important part of the car, always good to have extra rubber on the road.

-Coop

I was looking at the tires on TireRack. The 215s are $139 but the 225s are only available in W speed rating so theyre $170. Now I think I might do 235 all around as those are only $150 a piece. Then I could rotate my tires if I had the same size all around. If i have 17x7 with 42mm offset and 235/45 tires, will they rub in the front? If not, I will just do 235 all around. Or will that affect my handling by not having the fronts thinner?

[This message has been edited by derangedsheep (edited 06-08-2005).]

I have 215/45s in front. I'd really like a 235 but couldn't get a rim width and offset to make it work. Don't put the 235 on a 7" wheel, try to find a 7.5"
And just keep in mind that fatter tires up front will increase steering effort.

[This message has been edited by 88gtNewb (edited 06-08-2005).]

quote Originally posted by 88gtNewb: Don't put the 235 on a 7" wheel, try to find a 7.5"

I already did. They're mounted and balanced. They look fine, they don't look too big or anything. My dad runs 225 width on 6.5" rims on his van and he has no wear or handling problems. I don't see why I can't go another 10mm wider with a rim thats .5" (12.7MM) wider

It's been said many times before and I'll say it again...

quote I don't see why I can't go another 10mm wider with a rim thats .5" (12.7MM) wider

Because it's not just about section width, you have to consider sidewall and rim diameter. The larger the rim, the shorter the side wall, the less tire width you can use. You CAN put it on, it will work, it will hold air, and it will roll down the road.

What the tire manufacturer is saying is...

215/45/17 is designed for a 7" rim

225/45/17 is designed for a 7.5" rim (max on 7" rim)

235/45/17 is designed for a 8" rim (max on 7.5" rim)

That is what people are saying, hope that helps answer your question.

PS: the smaller size up front the better. I run 205 in front and 235 in rear, others are even more extreme running 215 up front with 255 rear. You don't want a big tire up front.

[This message has been edited by Skybax (edited 06-08-2005).]

quote Originally posted by Skybax: PS: the smaller size up front the better. I run 205 in front and 235 in rear, others are even more extreme running 215 up front with 255 rear. You don't want a big tire up front.

If the smaller the better up front, why aren't you running a 185 or 195 - or even smaller? Seriously though, what's your logic here? Drag cars run skinnies up front to reduce rolling resistance, Roadrace cars run wide tires up front for increased traction - which are you going for? I'll take the traction where I can get it myself!

BTW: I'm running 225/45/17's on my front 17x7 wheels, and 255/40/18's on 18x7.5 wheels - the steering is definitely heavier than it was with stock wheels & tires, but the increase in traction is worth every muscle used in a hard corner. The only complaint I've heard about the 255s was that they were a little difficult to get on the rim

255s on a 7.5"? I have 245s on an 8" and it looks about right. You must have some bulging going on, and that can't be good for traction. Best performance is going to be had from a rim that is near the maximum rim width for your tire, not the minimum.

Anyways, more tire up front is fine as long as you have strong arms.

quote Originally posted by 88gtNewb: 255s on a 7.5"? You must have some bulging going on, and that can't be good for traction

That's because a 255/40/18 is supposed to be on a 9" rim. (operating range is 8.5" to 10" rim width)

quote I have 245s on an 8" and it looks about right.

That's because even though it's designed for a 8.5" rim, the operating range is 8" to 9.5"... your within spec.

quote Originally posted by 88gtNewb: 255s on a 7.5"? I have 245s on an 8" and it looks about right. You must have some bulging going on, and that can't be good for traction.

No bulging - actually, everyone that has looked at the car thinks they look just about perfect. That, and until I install the SBC, my 3.1 doesn't put out enough gusto for me to worry about losing traction at the rear

http://fiero.mn.org/MFF_Spring_2005/P5230007sm.jpg

quote Originally posted by Skybax: Ask somebody like Will to explain it to you, or search the archives... I'm too tired to write a book. Seriously.....

I understand suggested operating sizes, etc... I'm running 7.5" wheels because that's what was available, and I'm running 255s because they were nearly new & free. Can't go wrong there. But if/when I need to replace the rears with hard earned cash, I'll most likely drop back to 245s (which is what was originally planned).

I was simply trying to point out that your statement of "the smaller size up front the better" is somewhat misleading. Why not go out and put on a really skinny wheel/tire combo with the idea that thinner is better? It'll definitely run better on the snow (as thinner tires cut through snow to get to the ground surface far more efficiently than a wide tire), but for dry/normal weather traction something wider provides better traction, which means better/higher cornering speeds. More contact patch = more traction.

BTW: I've read some great writing from Will about tire sizes recently, but failed to note anything that matches up with your theory of "the smaller size up front the better" https://www.fiero.nl/forum/Forum2/HTML/061141.html

quote Originally posted by Will: 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 message has been edited by MinnGreenGT (edited 06-08-2005).]

yes... so he would be much better off with the 215s (smaller) up front than 225s wouldn't he?

quote Originally posted by Skybax: yes... so he would be much better off with the 215s (smaller) up front than 225s wouldn't he?

I think you're right. I took 235 and multiplied by .8 and that gives me 188. So according to what will says, I need either 185s or 195s up front. I don't think I will go that small. I guess I will get the 215/45/17. The 225s might make steering a bit hard plus theyre $30 more per tire. I don't feel like spending an extra $60.

[This message has been edited by derangedsheep (edited 06-08-2005).]

I went with 215/45s on the front and 235/45s on the rear. They were originally mounted on 17x7s all the way around, but I swapped rims and now have 8" on the back.
I used that 'split' primarily because of cosmetics (88s like to poke out in the front), and because that's what everyone else was using, but also because of the Fiero's tendency to spin if you get clumsy in a corner.
Having the front wash out is generally preferable to having the back come around, unless you really know what you're doing. That's why automakers design their cars that way.
Having said all that, the 215 / 235 split seems to work well. Pushed to near the limit on an 88, it makes for some nice handling. The fronts and the rears both seem to start "screaming" at the same time. When I was at Waterford, I only started to spin once, and it was easy to correct.

I definitely wouldn't do the 235s on the front. I think you'll be looking at the trees coming at you in your rearview mirror in a big hurry.

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Raydar
88 3.4 coupe...........

Coming soon...
88 Formula, presently under the knife.
Read Nealz Nuze!

[This message has been edited by Raydar (edited 06-08-2005).]

quote Originally posted by Skybax: yes... so he would be much better off with the 215s (smaller) up front than 225s wouldn't he?

Most likely, but it would depend on the exact weight balance of the car (Will's 45/55 was a generalization to display the formula - it isn't exact as different year/model/drivetrain Fieros will vary that value) - I was just giving you a hard time about your broad statement "the smaller size up front the better" It should've read something more like "Your front tires should be proportionately smaller in relation to your rear tires to properly balance the car's handling"

Of course most of this (especially getting to the equation levels) has more to do with performance of the tires/vehicle at the handling limit. For day-to-day driving... you won't see the full effects of different tire choices. And yes, the 225s up front do make a noticable difference in the force needed to turn the steering wheel (especially if you have a smaller diameter aftermarket wheel).

I agree.