How much tire is too much?

[Blown73]

Is there such a thing? Can you put too much tire under a car that is being built for road/track? I know that the running theory is the more tire the better, but at what point does it become more aesthetic than functional?

My point being, I am looking to start fitting up tires/chassis/suspension on a 67 Nova, so my options are pretty well unlimited (within reason) and just don't really know where to start thinking about tire size. I was thinking a 315, 335, or even a 345, but is the added performance with the added cost?



Opinions are appreciated!

[SLO_Z28]

Going to a better tire has better results than going to a bigger tire. Going to a bigger tire in the better tire is beneficial, to a point. In 99% of cars you will never reach the point of diminishing returns on size, but it does happen eventually.

As an example a 275 Nitto NT05 is WAY 335 BF Goodrich KDW. A 225 Hoosier A6 is better than all of the above.

[parsonsj]

On a front engine, rear drive car, with a bit more than half the weight on the front tires, the limiting factor is the front tire. All of our PT iron fits in this category.

The best approach is to get the widest tire you can on the front, then balance that on the rear... trying to keep the difference between front and rear to 30mm, 50mm max.

As an example, if you can get a 265 up front (and that takes a *lot* of doing on a 67 Nova), then you ought to go with a 295 on the back, but no more than a 315.

[MrQuick]

...when two of them cost more than what you bought your car for. lol


but seriously, when it comes to the weight and well room your gonna wanna go for balance. I agree with John, 295/255 combo would be a great start.

[JRouche]

The best approach is to get the widest tire you can on the front, then balance that on the rear...

YUP!! I agree with that!! You can always fit some massive meats on the back side, and you should. But some of the more difficult builds will be fitting some wide rubber on the front, without interference probs. JR

[FirebirdSteve]

Always thought tire size was like sex.......can never have to much!!!

[Blown73]

Always thought tire size was like sex.......can never have to much!!!

I thought so too, but even then, at some point, you are just blowing dust balls.

I am working with a guy who is helping me to get the frame (full frame) dialed in, so we are going to narrow the front frame rails as much as we can to fit the biggest tire possible in the front. Not sure what that will be yet, but I am still looking for ideas....

[parsonsj]

we are going to narrow the front frame rails as much as we can to fit the biggest tire possible in the front.

Your limiting factor then is when the narrowing front track (center of contact patch to center of contact patch) compromises the gain that the additional tire width gives you. A 67 Nova is very narrow, and those squared off fender openings push the tire even more inside. I think a practical limit is a 9 or 10 inch wheel (265-295 tire).

[Blown73]

Your limiting factor then is when the narrowing front track (center of contact patch to center of contact patch) compromises the gain that the additional tire width gives you. A 67 Nova is very narrow, and those squared off fender openings push the tire even more inside. I think a practical limit is a 9 or 10 inch wheel (265-295 tire).

I would think that is plenty of tire for what I want to do. I am not building a full on race car with this one. I want something I can get into and drive anywhere I want to go. That might be the grocery store or across the country. Just looking to make the car a very capable car to tackle _______ (fill in the blank) and have fun doing it.

[sik68]

On a front engine, rear drive car, with a bit more than half the weight on the front tires, the limiting factor is the front tire. All of our PT iron fits in this category.

The best approach is to get the widest tire you can on the front, then balance that on the rear... trying to keep the difference between front and rear to 30mm, 50mm max.

As an example, if you can get a 265 up front (and that takes a *lot* of doing on a 67 Nova), then you ought to go with a 295 on the back, but no more than a 315.

[nine lives johnny]

it's all about heat, weight, the track, down force, and compound. you need to be able to get your tires up to temp. larger tires can handle more heat.. but there are more factors then that.

[SRD art]

Great thread! I've got 255-40 & 275-40 but am setting up the rear to accept 315-35-17s when I can spend the cash on them. According to what you're saying, that's too wide. Where does this info span from, and what happens negatively when you get a little too wide out back?

[Blown73]

Your limiting factor then is when the narrowing front track (center of contact patch to center of contact patch) compromises the gain that the additional tire width gives you. A 67 Nova is very narrow, and those squared off fender openings push the tire even more inside. I think a practical limit is a 9 or 10 inch wheel (265-295 tire).

One more question as I think more about this. You say the center of the contact patches are narrowed (as the 67 is narrow already) are you thinking of rolling problems when you refer to this? Kind of like the stability of standing with your feet together versus having your feet apart?