Tire grip - quantity or quality?

In the course of a CAM-ish build using 15 inch diameter rims (because it's intentional ridiculousness), I find myself in a quandary of choosing between 15x10 wheels with 300+tw 295/50 tires (Cooper Cobra or BFG Radiat T/A), or 15x8 wheels with 200tw 245/50 tires.  Not going on a particularly light car (1979 Granada), so I'm concerned with melting the 200tw tires of the rims.  I'm not planning on winning anything, or building for any specific competition, so this is more of a planning decision.  I like the idea of the bigger tires with some outrageous 70s flares, but I'd like to have better grip.  Inputs?

What is the intended use of the car?  Track days?  Street? Autocross?  etc.  

The car will see some street duty, with regular autocross and occasional track days. 

I suspect the wider tire will be the better option but I've never done a direct comparison.  I haven't looked at the numbers but you might be able to run 15x9 wheels and either tire size.  That would allow you to see what works the best.

I guess the question is cost and wear not being a factor, where is the line between a harder/wider tire and a softer/narrower tire?

I have considered just testing them on multiple sets of rims... I can also get an R7 in 275/50-15, which I suspect is superior to both of my streetable options...

There's no line, just a continuum of options. I'd guess you'll get similar grip between the two, but the 295-wide tires will last longer.

The size of the contact patch doesn't really change when going to wider tires.  It just changes shape and becomes wider and shorter (more rectangle less square).  This was very noticeable when I jumped all the way to 275 Hoosiers.  Braking and accelerating actually take a hit but greater cornering speed due to the loading and shape of the available grip.

Also consider that the wider tire will be heavier and increase drag.

In reply to jj :

Right, Cooper Cobra and BF Goodrich Radial T/A aren't exactly autocross tires...

I would go with the 200TW tire

I ran into the same dilemna. I went with 17's because the wheels were stupid cheap and threw on a 275/55/17 400TW tire. They have zero grip in any condition. straight line? smoke 'em. turn in? mush. braking? locked. Changing to a 255/40 RE-71R for the front and leaving the 275's on hte rear with plans to be sideways and smoke e'r'where.

If what I'm seeing is right, curb weight on those was like 3250.   Not exactly 'heavy' by modern standards, even if not particularly light either. If we were talking about good 280-300TW tires you might be able to make a case for them, but we're not.  My guess is that the 245mm 200TW with shorter sidewall will be faster than those particular 295mm 300+TW with taller sidewall.  The crap 300+TW tires will last longer on the street and look cool though.

EDIT: Followup question - What 200TW tire comes in 245/50-15?

FIYAPOWA said:

I guess the question is cost and wear not being a factor, where is the line between a harder/wider tire and a softer/narrower tire?

Have often wondered this myself...  I lean narrower/lighter/stickier.  I guess like RMH says its weight versus lifespan. 

Driven5 said:
 

EDIT: Followup question - What 200TW tire comes in 245/50-15?

Uhhhhh, Tire Rack lists only Hoosier A7s in 245/50-15. BF Goodrich Rival S, whatever Maxxis' tire is called and the Hankook RS4 are available in 245/45-15.

In reply to NickD :

Exactly.  That's why I asked.

Just a guess, but I think any 200 tw tire in any size would be roughly six seconds per minute faster on track than any size Cooper Cobra or Radial TA you could find.

It is very hard to find a 15 or even a 16 in sizes to fit an American car that is not a poser tires, or a full on race tire.  You are kinda limited to Hoosier quality or Cobras/TA.  I have a set of the BFG Sport Comp 2 in a 245/50 16 on my Camaro, but if I wanted something streetable and better, I would need to buy 17 or 18 inch wheels.  I like the BFG Sport Comp, but its no race tire.

I race Lemons in a 3500lbs car. Switching from a low TW street tire to a 200TW "race" tire actually gained us tire life and cut seconds off per lap. I know people have had good luck racing in heavy cars with 300tw+ tires, but that wasn't the case for us. Also, I've heard from Lemons people that the Radial TA is crap in racing.

In my experience, tire compound/construction trumps all.

I’ve got a set of 200 mm wide radial slicks (Hoosier C3000) and I’d bet my life that they’ll grip better than even the best 225/45/15 street tires.

This would be a great artical for the magazine.

The 200 treadware tires will be much faster than those big tires with horrible grip. Not even remotely close 

Pics and specs of said Granada please?

In reply to Stanger2000 :

It is "under construction" at the moment - I have a rendering coming in the next couple weeks, will post.

It's currently a 6 cylinder automatic car, getting a 302 2-barrel (on purpose) and a 4-speed (Toploader), again, on purpose.  Sticking with stock front suspension geometry, stock leaf rear on the Ford 8" axle.  If I can get the weight to around 3100 lbs I'll be happy, since I'm not doing any massive weight-shedding in the build process.  End goal is a vintage NASCAR vibe.

buzzboy said:

I race Lemons in a 3500lbs car. Switching from a low TW street tire to a 200TW "race" tire actually gained us tire life and cut seconds off per lap. I know people have had good luck racing in heavy cars with 300tw+ tires, but that wasn't the case for us. Also, I've heard from Lemons people that the Radial TA is crap in racing.

That's interesting - how did a softer compound contribute to longer tire life?  Did the car not slide as much?

KyAllroad (Jeremy) said:

The size of the contact patch doesn't really change when going to wider tires.  It just changes shape and becomes wider and shorter (more rectangle less square).  

For some reason does not make sense to me. If the rolling diameter is the same between say, a 225 wide tyre and a 275, why would the contact patch not get bigger?

NickD said:

Driven5 said:
 

EDIT: Followup question - What 200TW tire comes in 245/50-15?

Uhhhhh, Tire Rack lists only Hoosier A7s in 245/50-15. BF Goodrich Rival S, whatever Maxxis' tire is called and the Hankook RS4 are available in 245/45-15.

Correct - I think I misspoke.  R-S4s, Rivals, and the Maxxis Victra VR-1 are available in 245/40-15.  I believe those are the tires I was considering.

jj said:

My thoughts:  Smaller 200tw will be cheaper, lighter, and same or better grip.  That and I don't think any good 300tw come in 15s.

Correct. Basically every 300+ TW 15 inch tire minus the Contisport contacts in 205/50/15 are complete garbage. 

My vote is Hankook RS4 or Rival S 1.5 245/40/15 on 15x10's.