I'm thinking about ordering some wheels from Diamond. I have no idea what backspacing to get and I'm torn between getting 15x7's, 16x6.5 or 16x7's.
Can someone help me out?
I'm honestly clueless in this department.
Also, right now I'm currently running stock waffles. I'm looking to buy wheels so that I can run a tire with as stiff of sidewall possible for when I Autocross.
All help is Appreciated.
-Crispin

 

Also, the only reason why I'm considering 15x7's is because of tire availability and price per tire. Otherwise, I really want to get the 16's.

 

I went through the exact same thing about 2 weeks ago. I settled on 15x7's b/c of tire availability and also most people that do SCCA will tell you to buy 15s. I ended up getting the Rota RBs with a 25mm offset which makes your wheels stance wider (40mm overall). As far as I can tell with my new wheels on I would not go with any less of an offset, I also rolled the fender lips. I found the rota wheels for 115 a piece. I looked at the diamond racing wheels and they seems good but I wanted a diff pattern sooo... For tires I settled on the Kumho XS tires 205 50 15s because they are cheap. Either discount tire or tire rack has them for 91$ a piece.. not bad. Next up I think im gonna get a set of 225 40~50 15s. If you scroll down a bit on the 1st gen forum page you will see a thread I started called wheel fit... I think. Hope this helps.
VCS

 

^why wouldn't you go with less offset? Would it rub the spring?

 

15x7 with 4 inch offset is what i have, pics here crispin
http://417rotary.com/forum/viewtopic.php?f=2&t=282

offset not backspacing sorry

 

Man those look good!
4" Inch eh? That's a lot more then 25mm.

 

i ment offset not backspacing

 

The closer the number of the offset is to zero the farther out the edge of the rim will be from the center line of the wheel, so eventually the wheels will stick out way past the fender. A smaller positive number offset will put your wheels farther from the spring. Your stock offset is 45mm, so in my case when I went with a 25mm offset there is a 20mm difference which means the outside edge of the rim is 20mm farther from the center line of the wheel. 20mm is between .75in~.8in when you do the calculation. A friend of mine has a 1st gen rx7 and he bought a set of Drag wheels with a 40mm offset and he ended up putting a 5mm spacer because they rubbed just a little bit.
vcs

 

https://www.rsracing.com/tech-wheel.html#patterns

im running 4 in offset with 0 bs IIRC

 

nice setup TS87FC3S.

 

Thanks its a work in progress but its getting there

 

I use to have a set of 15x7's with 5 1/4" offset and I had to run spacers.
So, since my car will mostly see street use I think I'll just go with 4" of offest? That looks/sounds like the way to go. Or am I still missing something?

 

My wheel setup.

 

my front wheels are a lil further out of the the car then the back but the track width is diff front to rear and with the same rims f and b ur going to have that and i run good amount of camber , back fits amazingly

 

Backspace and offset are not interchangeable. You keep saying offset but mean backspace. Diamond Racing doesn't care about offset, only backspace because it can be measured more accurately. So be sure to get it right if you order from them. I have 13x8's with a 4" backspace. I went with 13's for less weight and cheaper race tires, I run a P215/50R13 Kumho V710 so it is plenty stiff. They do stick out from the fender a bit though. If you go with a 7" wheel with the same offset, it won't stick out as much. Here's a pic of mine, but it's hard to see how they stick out from this angle.

http://img543.imageshack.us/i/rx7blue1.jpg/

 

Thanks for clearing that up. Sounds like I don't want anymore than 4" of backspace.