Im sure this must have been discussed before but Id like to have a better idea about tire size vs. performance. I plan to get a 3800sc swap but figure why not get new tires/ wheels first, just a little cosmetics goes a long way. I have some very crappy steel black rims w/ random plastic hubcap deals I would like to know w/ the engine swap upcomming (when I come up w/ the funds) what size should I go with? The car is my daily driver but I will want to race on ocassion I dont believe the stock 185 75 14s are the best for performance (if I recall the size corectly) Thank you in advance for your imput. Or just feel free to tell me what size you have, and maybe why.

[This message has been edited by revshawn (edited 09-09-2007).]

21 people have looked at this and no one has tires?

[This message has been edited by revshawn (edited 09-09-2007).]

lol its all your own preference, 225's out back minimum, 225 max up front, im running 215-60-15's on the front and 225-60-15's on the rear with my 3400 V6 conversion, it holds the road very well, for a 3800sc 225's will be great, my 3400 puts more TQ off the line than a 3800sc does and thats where tires count, as far as rims...i like the stock black lace gt rims..but you can be modern like everyone else and throw some 18's in the front and 24's out back..because your car REALLY moves with thoes proper sized rims!

Yeah, a lot of it is personal preference.

But just as a quick guesstimation, I'd say maybe 205-215mm wide in front and 235-245mm wide in back. Although, if you want to be able to rotate the tires, you'll need to compromise (like maybe 225mm on all 4 wheels). I'd also suggest rims at least 16" diameter, so you can use higher performance tires.

I run 205/50/15 on stock rims. 17s and 15s are the two most popular rim sizes so those size tires are the cheapest. Traction isn't always good. I run 205/50s on 15s and 205/40 on 17s. Less sidewall is better for handling...too a certain extent. 205 is the skinniest I would run.

I guess in all honesty I really dont understand exactly how the numbers in tire size relate to performance. Which numbers mean what I'll probably never live this admission down but I really hope some can clear this up for me. Thank you

The first number, 205, 215, 225 and so on is the section width, basically the width of the tread in mm. Divide that number by 25.4 to get inches so a 225 tire is 8.858" wide.

The second number, 40, 45, 50, 60, 70 and so on is the aspect ratio. It is the height of the sidewall expressed as percentage of the tread width. So on a 50 series tire the sidewall is 50% or 1/2 as high as the tread is wide and a 70 series tire of the same tread width has a higher sidewall.

The third number 15, 16, 17 and so on is the diameter of the hole in te center of the tire and also the height of the wheel.

As long as we are doing definitions, the wheel is the entire metal part to which the tire mounts. The rim is only the outer edge of the wheel, the part that the tire touches.

[This message has been edited by Steve25 (edited 09-10-2007).]

Great thx, so now how does all that relate to performance?

Wider tire= More traction
So, the three digit numbers (205, 215, 225) are the width, you want the biggest your wheels/car can handle

Tall sidewall= smooth ride, not so great cornering
Short Sidewall= Slightly harsh ride, better cornering
The 2 digit numbers (40, 50, 70) you want smaller, in theory. In reality you want what will look best in your car. you also dont wanna mess your speedo

Thank you very much.

quote Originally posted by 86FieroCentPa: Wider tire= More traction

It's not that simple. While wide tires are good for dry traction, they're not so good for wet traction. Wider tires are more susceptible to hydroplaning.

Wider tires are also less tolerant of camber settings. While this won't be a concern with conservative camber settings, it will become a concern if you want to use lots of negative camber for racing. The wider the tire, the more the outside edge of the tread will be lifted, which will result in reduced traction and uneven tire wear. This becomes a serious concern when the tires have a low profile and stiff sidewalls.

[This message has been edited by Blacktree (edited 09-11-2007).]

I somehow doubt that someone that didnt understand basic tire sizing is going to be worring about his camber for racing. I was giving the simple explanation

So keeping all this in mind what can a notchie handle without some kind of mods/spacers etc.... I found some nice tires in 17s do they fit ok? no steering problems etc...

I have 17x7" wheels on my '87 notchie, with 215/45 tires all around. The suspension is lowered an inch. There are no interference or alignment problems.

Just keep in mind I have a "lowly" 2.8 V6. So I can get away with 215mm tires in back.

In the past, I've used tires as wide as 245mm on the back (using stock 14" wheels). But those tires came very close to rubbing the struts. With a more aggressive camber setting, they probably would've rubbed. So based on that, I'd say 245mm is iffy on the stock rear suspension (depending on the wheel offset). But 235mm should be safe.