91 with 16" in front - tire height?

[midNight Sun Xpress]

I cannot figure out which tire height will be the correct. I have been driving with 225/40/16 for the last two years, and I have had a couple of "TCS"-incidents on track days. Also, my front wheels looks like they are a size too small for the fender curve.

A few days ago, I measured the diameter on two of my friends NSXes who both run 225/35/18 in front. They are appx. 1" larger then mine. Using a tire calculator, I got 225/45/16 as the closest to 225/35/18.

I searched the Prime and found the newer NSXes using 45 as standard height.

So, what will be the most correct height: 40 or 45?

 

[NSX2398]

'91s came with 15" front rims but if you're talking about the stock 16" front size that came out a few years later, it was 215-45-16 which are difficult to find depending on the brand.

 

[midNight Sun Xpress]

I bought my car with aftermarket wheels some years ago. After I invested in a new set of Enkeis, I apparently calculated the tires in front to be 40 in height. As I said in my first post, they looks too small for the arch and also is 1" lower in diameter compared to my friends NSXs

I would like to know what is the recommended tire size when running 16&17 on a 91 with 225/16 in the front: 225/40/16 or 225/45/16?

 

[NSX2398]

This may be an academic exercise. According to Tire Rack, nobody makes a 225-40-16 tire any more so if you're looking for new tires, that narrows it down to your other choice. But as I said, the stock size for the front is 215-45-16 .. why wouldn't you go with that?

 

[angus]

+1 on that , stick to OEM in that rim size.

 

[midNight Sun Xpress]

225/45/16 has been ordered. :smile:

I run 225 for the looks, but could of course choose 215s. As I said, I must have miscalculated the set I bought for my Enkeis. It did look a bit too small, but I was confident my math was 100 % correct.

Anyway, now I will have 45 height and hopefully eliminate my TCS problems on track days.

 

[Hapa88]

You should cancel your order and get the 215/45/16.

Sounds like your a little confused at how tire sizes are measured. The 40 and 45 number on a tire is the aspect ratio. This represents sidewall height as a percentage of the width of the tire. Therefore a 225/45/16 will be a larger diameter tire and will have a taller sidewall than a 215/45/16.
You never mentioned what size rear tire you have, so it's impossible to determine what's causing the TCS issues without that information.

Combinations that work are with TCS:
215/45/16 fronts and 245/40/17 rears.
215/45/16 fronts and 255/40/17 rears

 

[angus]

Yes, and since your car is a '91, the problem with TCS gets even worse since TCS is programmed for 15/16 tires, so even departing a small amount from OEM 16/17 sizes will cause problems.

 

[midNight Sun Xpress]

Hapa88: No, I am not confused how tires are measured. I have been running cars and bikes for some decades now. I do know that the diameter of a 45 is bigger then the 40s diameter. Again: I miscalculated, maybe because the old tires where wrong size, maybe I just made an error. That is not the point!

I run 255/40/17 rears which are slightly higher than original. Logically the 225/45/16 should be the best option, and also be close to the diameter of my friends NSXes which do not have any TCS problems.

Angus: My TCS came on at 2-3 occasions after some rounds at the track and then cooling down half an hour. Soon after starting up again, I had the TCS after appx. half a mile driving. Never had any problem on the street but I know the TCS can be very sensitive on the NSX.

If the TCS problem still persist with the 225, I'll promise to buy 215s the next time. :wink:

 

[goldNSX]

Please remind that TCS activity is not a single function of tire size. Of course it's a basic variable. On the track I'd expect TCS coming on even with a perfect size combo.

 

[Hapa88]

Hapa88: No, I am not confused how tires are measured. I have been running cars and bikes for some decades now. I do know that the diameter of a 45 is bigger then the 40s diameter. Again: I miscalculated, maybe because the old tires where wrong size, maybe I just made an error. That is not the point!

I still think you misunderstood what I was saying. No, a 45 is not necessarily larger in diameter than a 40 . . It all depends on the tread width. For example: a 215/45/16 is smaller in diameter than a 245/40/16.

What I was saying is that a 225/45/16 is larger in diameter than a 215/45/16 (24" vs 23.6" diameter). Many people don't know that.

Here's a nifty calculator to help you in the future:
http://www.1010tires.com/TireSizeCalculator.asp