I know you love fitment questions, but none of the guides that I have seen mention anything about outer diameter.

First, wheels. Same size all around, 17x9 +43 FN01R-Cs. I like how they look so much like the OEM wheels (at least in the pictures I've seen). The Jimlab sheet has them fitting perfectly, with 0.2" of clearance on the outside up front, and 0.7" on the back. 0.8" of clearance inside all around.

As for tires, the RT-615s come in a 275/40/17. According to the manufacturer's specs, they'll fit on a 9" wide wheel. Thing is, the outer diameter is 25.6". The OEM tires are ~24.8" OD. The car is lowered (too much so, in fact, on a set of S-techs, but I'm going to deal with that later), and I'm having doubts as to whether or not the larger-than-stock-OD tires will fit.

Anybody have any experience with this?

 

It won't work. You'll be into the fender liners continuously. Right up until you rub through them and destroy the wiring harnesses, at which point your car won't even run.

 

You CAN run that size on a 9" wheel, but it's pushing it width-wise. In terms of diameter, don't sweat it too much (at least from a rolling diameter perspective), it's very difficult to maintain stock diameter on 17" wheels. Plenty of people run 275/40/17's.

The only issue you'll have is some front end rubbing, particularly on a lowered car. I run 275/40/ all around on my track wheels, and they rub the liner sometimes, particularly at full lock (which you rarely see on track). I've also got rolled fenders, and you'll want them too.

If you want to run the same size all around, you could try 255/40/17 (perfect) or even 265/40/17. If you don't care about same size all around, you could try a 245/40/17 or 255/40/17 front, with either a 255/40, 265/40, or 275/40 rear.

 

I have RT-615 255/40 fronts (on 17x8.5) and 275/40 (on 17x9.5) on my car. It fits fine for me, but the 255 in front is pushing it a bit. And all kinds of things like driving style, alignment, etc. affect the tire's propensity to rub. YMMV

-Max

 

What shocks are you running?

 

Koni yellows.

I'm willing to roll fenders or whatever to make them clear. I'm really just interested in getting both as much tire as possible and even amounts of tire on all four corners (for rotateability, if anything), and not spending obscene amounts of money.

Max: how are the 255s pushing it? Rather, where are you running out of clearance?

 

They are tall. They haven't rubbed yet, that I am aware of. My suspension is not stock. I have GAB super-R shocks, converted to coil-overs, with 450 lbs/in springs, and a Tri-Point 0.188"-wall modular anti-roll bar (using the middle holes for end links) with Widefoot mounts up front.

My 245/40-17 S-03s caught the fender lip on the passenger side a few times. Drat! I think that happened with the stock anti-roll bar, though. I recommend rolling your fenders from the start -- once it catches, there is a high risk of losing paint.

Also maybe start conservatively. You will wear your tires out soon enough and you'll have a chance to push the limits a little more if everything worked out with the last set.

-Max

 

Guys, he is lowered 1+ inches up front on the typical soft lowering springs. I think he'd chew through the front fender liners pretty damn quick with 275/40s.

 

The S-Tech are 436 F, so that aren't that soft.

xthephilx,

I'm not all that familiar with the different Koni brands, do you have the adjustable perch? If so, what is it set at? At 17x9 +43 with 255's in the front, I had to roll the fenders that that was it.

 

Just get the 255/40 all around, and get your fenders rolled.

 

The konis that I have have the adjustable perch. It's set at the highest setting (I believe the stock height setting).

rynberg: Which springs lower the car less and/or have higher rates? I'm actually trying to raise the car due to exhaust clearance issues.

 

RSR Race Springs

 

I have no rubbing issues with my setup. I have Tein S-tech springs on R1 struts for now. Front wheels are 17X8.5 +45mm with a 255/40. Fits real nice with a bit of room to spare. Rear is 17X9.5 +40mm with a 275/40, again with plenty of room to spare. No rubbing at all.

 

My 255/40/17 front kuhmo mx have rubbed holes in the liner on both sides. I am running them on a +44 , 9" wide wheel with buddy club coilovers. I'm planning on raising the fronts a little and having the car corner weighted again.

 

Given the konis on RSR springs then, would I be able to cram 275s in (yes, I know I keep going over the whole 275s up front, I'm rather set on them) with relocating the over-fender harnesses? What else is there in the way?

And yeah, I'm already going to roll the front fenders.

 

I don't think you are going to get anything larger up front without being able to "fine tune" things with a good set of coilovers.

 

"Anything larger" being "anything larger than 255s" or "anything larger than 275s"?

 

Larger than 255's.

 

The 275s are never going to fit well in the front, no matter what you do. Go for the 255s.

-Max

 

Poo. Oh well. 255s up front it is then.

Anything I can do to easily dial out the understeer I'll end up with with the larger rear tires?

And should I go with 17x10s in the rear to maximize tread with the 275s?

 

See how the car handles first. I think it will be fine without having to do additional tweaks. If it really doesn't work (seriously; drive it first), you can install a stiffer rear anti-roll bar. But I don't think you will want to.

I checked out your LS-1 conversion site. Looks good, and thanks for sharing the pics and info.

-Max

 

Blah, I have to ask just because I really like the idea of 275s all around. Although maybe I'm just stupid and think I really need the extra 2cm of traction

What if I went to +35 offset wheels instead of +43 offset wheels, switched springs, and flared the front fenders?

Would the low offset wheels cause any sort of excessive wear on the wheel bearings since the center of the wheels is being moved so far out from stock (+50 is stock I believe)?

 

Max: Thanks for looking at the site

As it stands right now, I'm not sitting with my finger hovering over the "buy" button, I'm probably a month or two out from doing anything. I'm just trying to figure out my options. And more, I don't want to spend money on wheels/tires that will end up being not enough.

 

PM "Spank" if you just have to have something that large up front. He's running 285's up front.

https://www.rx7club.com/members/spank-488/

You can talk to him about what he needed to do for fitment (but I guarantee he is running coilovers for starters).

 

Yeah, as Max says, drive it first.

The whole "you'll understeer like a pig if you have a staggered setup!" bit is very overblown. Firstly, it depends greatlyu on the rest of your setup, which has changed from stock anyway. Secondly, it'll be great for the street, you don't want to run those huge fronts on the street. The only timer you'd really want those big fronts will be for certain corners on certain tracks, IF you track it.

I love my 255/275 setup for street, then only run the 275's all around on track.