I've been going through the archives a lot to try and answer different questions that I have as I start moding my first RX7. I was in someone elses who had lowered their 7 and put on 17" tires. He consequently KILLED his turning radius. If you took a corner too quick or too tight it rubbed like CRAZY. He also practically bottomed out in potholes and couldn't go up into driveways very easily, but meant it to be a DD. Anyways, I've come to the point where I'm ready to look at replacing the stock tires on my car. Having seen what a bad choice can be for a DD I thought that I would keep the stock 16" wheel size. But then I noticed that everything that I was finding in an aftermarket wheel was only 16X7, but that the stock's were 16X8. Therefore, being narrower, a 16X7 would perform less than stock because it has less "grip" on the road that a 16X8. Correct?

So my question is this: If I go with a 17X8 wheel, what tire size do I need so that I retain the same overall demensions as stock? Also, if I get a 17X8.5 or 17X9 will I have to worry about rubbing and losing my turning radius like the other guy did?

Thanks for your help!

 

Ok, I've finally found two good overall diameter calculators!

http://www.1010tires.com/TireSizeCalculator.asp

http://www.miata.net/garage/tirecalc.html


So, I'm set on finding out what size tire I need to have on what diameter rim in order keep the same overall diameter.


HOWEVER, I still could use input on what width I can get and NOT rub when I turn tight corners etc. Also, Can someone please verify for me that stock wheel specs are: 16X8 / 50 / 5-114.3

Thanks again!

 

My question could better be asked this way.

What offset do I need in a wider tire (8.5 or 9) in order to not have to worry about rubbing and/or losing turning radius?

 

Anything between a +45 to +50.

 

Some of it also depends on your suspension setup and the general geography of where you live. My car has been running 17 x 9 +45 for year with H&R springs on stock and Koni shocks with 255/40/17 tires.

Until recently, I never had a problem with rubbing. I recently moved to an area with more hills and have experienced rubbing of the tires on the fender lip when taking a corner that transitions to an uphill. It seems that the suspension is either a bit too low or the wheel/tire setup or a combination of both cause it to rub when the terrain goes uphill in a corner.

My ride height is around 25.25" to 25.5" up front.

 

I've recently been looking at the same thing. If you search in the FD fitment thread, you will find links to a nice Excel spreadsheet that will answer all those questions. According to it, the minimum offsets for 17" wheels would be:
8" - ET 31mm front, 25mm rear
8.5" - ET 38mm front, 31mm rear
9" - ET 44mm front, 38mm rear

Essentially, what Malik already posted. As I understand it, those are minimum offsets to give about a 1/4" minimum clearance. The stock 16x8 have an offset of 50mm.

For a 17" wheel, the tire sizes that will most closely match stock diameter would be:
225/45
235/40
245/40
255/35
265/35
275/35
285/35

Check out the spreadsheet. It is pretty handy. Of course, I'm just hoping my stock 94 hasn't sagged over the years and that the new wheels and tires I ordered will actually fit.

 

I used to run 235/40-17's and they would rub the inner liner because my aftermarket springs were too soft.

A new set of Koni shocks helped a bit, but that's not the right way to fix it.

Oh yeah, and the wheels were +45.

 

235/40-17 is actually a bit smaller (about 1/2") than the stock diameter. I'm surprised they rubbed.

 

Thanks for all the feedback!

I've received very high praise for a set of four Enkei RPF1s in 17x9.0/35/5*114.3 on the FD since I'll be pushing 400HP once I'm done under the hood.

So that would be a 255.40.17 or 255.35.17 tire? They shouldn't hamper steering/acceleration/etc from what I can tell since they're only 15/16 pounds each.


But will these rub???

Thanks again for all the help!

 

Oh, 68K original miles. I got the FD at 63K miles. There are a set of Koni shocks on it, but I don't know if it's lowered, etc. How can I tell where it was set in compared to stock height? A ruler I'm sure, but I'm still learning about my car and loving every bit of it too! Thanks again.

 

Depending on your suspension setup, you'll definitely have to roll the fenders in the least. That's a fairly aggressive offset. If you look here, Rishie ran a special group buy for the +45 as it's a less aggressive fitment for the car (i.e. less things to deal with):

https://www.rx7club.com/showthread.php?t=601552