O.K. guys I did a bunch of measuring today to determine our maximum clearances on a sport sedan for max rim/tire widths. All measuring was done with stock springs and full suspension compression. Here is the info....

Clear distance from hub face to the outer wheel well lip is 3 1/4"

Clear distance from hub face to inner radius arm bolt head is 8 3/16" (this was the closest part to the rim and tire on the inner wheel well/suspension on the car)

Total clearance for a wheel and tire flush with outside of wheel well is
11 7/16"

If we use a stock 8.5" rim width with +50 offset, we have 1 15/16" inner well clearance and the rim sits 15/16" inboard of the outer wheel well edge.

If we use a 10" rim width with a +47 offset, we have 1 5/16" inner well clearance and less than 1/16" inboard of the outer wheel edge.

If we use a 10" rim width with a +55 offset, we have 1" inner well/suspension clearance and about 5/16" inboard of the outer wheel edge.

This is good news for fitting just the rim width but what about with the tires??

275 width tire (actually 10.8" wide) on 10" rim with +55 offset would give us
5/8" inner clearance and a flush outer edge.

285 width tire (actually 11.2" wide) on 10" rim with +55 offset would give us
3/8" inner clearance and 3/16" past the outer well edge.

295 width tire (actually 11.6" wide) on 10" rim with +55 offset would give us
between 3/16" and 1/4" inner clearance and 3/8" past the outer well edge.

As a test, I do happen to have a set of 17" sport rims off a 2004 6mt sedan that I had widened to approx a +70 mm offset to handle a 275/50 Azenis RT-615 drag radial. At full suspension compression I have approx 3/16" clear on the inner radius rod bolt head and I have the outer rim edge about 3/4" inboard of the wheel well edge. It is reeeal tight on the inside but it runs fine. (NOTE: The wheel picked up more clearance on the bolt head as the car settled. It was tightest when the wheel gap was at it's widest and the car was jacked up.) Under some hard cornering I might have some rubbing just because the sidewall is a 50 series height. A lower aspect ratio on a 19" or 20" tire would cure this problem for sure. I had to run a 5mm spacer on these rims with the old car to clear the old steel radius rod design. The newer car does have a little more clearance for sure. No spacer needed.

I hope this info helps anyone looking for a wider rim combo. Cheers.

 

Very good information.

A few questions though ...

Is your car lowered? If so, do you have camber arms installed?

Can you clarify what you mean by full suspension compression? Do you mean your car was on an alignment rack with the tires normally loaded? Or do you mean you loaded up the car with weight to add compression to your springs (as if the car was lowered)?

IMO, to really determine max size, measurements should be made using a lowered car with camber arms on both an alignment rack AND on a regular hoist to also check clearance with the suspension unloaded. The IRS in these cars are very dynamic and vary a lot depending on suspension configuration and loading. For example, here are a few photos of the rear with unloaded suspension:







These are taken with stock wheels and tires, but they look like they are a tight fit already.

Current setups seem to indicate a minimum of +40mm is needed to stay fender flush.

There are photos of dbaquiran's lowered 07 sedan with 20x10, +40mm offset and 275 tires. His tires were fender flush as well and according to his emails to me, he did not have rubbing problems.

There are 2 other cars in this forum with 20x10 but as far as I know, they are not lowered yet.

None of these have camber arms. Adding camber arms would require additional offset as the top of tires will tip outward.

 

The car is stock supension. Full suspension compression is when the full weight of the car is on the wheel as if the car was sitting on the ground. This is done by removing the wheel and lowering the car onto a jackstand so the car sits level as if the wheel were on the car. I have seen photos of cars with a +40 offset and I think the photos are decieving. I think you would see more rim width sticking out past the fender edge with a shot from the top or rear. You never see many shots looking from the top of the fender down at the rim/tire. Most guys run a 275 on the 10" rim which does have a bit of a sidewall curve and under normal suspension travel does clear the fender edge as it arcs upward with a +40 offset. As I said earlier, when the suspension compresses, you do actually increase clearance on the rear radius arm as camber increases. I have spoken with dbaquiran about his car and he does say his 275's are tha absolute max for outer edge clearance with a +40 offset. I still think there is much more room on the inside for more offset and more tire width. I had a set of SSR GT-3's on my 2004 sedan with a +55 offset , lowered 1" and a 275/30 rear tire. Camber was within spec. It worked perfectly and I still had room on the outside of the rim to fender clearance....even with a 1/4" fender lip that has been eliminated on the 2007 car. If you were bagging or lowering your car much past 1" I think your supposition on the camber is arms would be correct. With 1" lowering most guys seem to be very close to being within the stock camber specs so camber arms are not needed. These measurements were taken as a guide for what clearances you have under most driving conditions, when the car sits on the ground under it's own weight.

 

I agree with you, I think the +40mm on 20x10 is the farthest out one can go. I am leaning toward +48mm right now assuming 275 tires, but I really want to go for 285 (just because no one has done it yet).

+50mm seems do-able, but +55mm seems a little too much. Do you know if a 285 on a +55mm has ever been done on the earlier model? Since you've spent some time under there and looking at the above pics, do you think a 285 on a +55mm tire will still go on if the car were jacked up (suspension un-loaded)?

I'm still a little skeptical about the camber ... I think it will make a difference in selecting offset. Doing the trig and assuming a 26" OD (13" radius) tire, every one degree of camber should tip the tire roughly 5.76mm.

I wish I could get my car on a rack and get under it to make some measurements (lowered car with camber arms). I think measuring clearances with a tire installed maybe a little more accurate. Anyone have access to an alignment rack in so cal?

 

come down to San Diego Terry, i've got two alignment racks. I think the +48 with the 285 will work nicely on the 07. The +55 IMO is too much offset, it will also defeat the purpose of a 10" wheel in the back as you're probably going for the look of a deep dish rim (atleast that's how i think about it). The +48 would be perfect.
-GP-

 

"Do you know if a 285 on a +55mm has ever been done on the earlier model?"

I could have fit a 285 no problem with the +55 offset on the 04 sedan but I didn't want too much tire bulge past the rim edge.

"I'm still a little skeptical about the camber ... I think it will make a difference in selecting offset. Doing the trig and assuming a 26" OD (13" radius) tire, every one degree of camber should tip the tire roughly 5.76mm."

When I took the measurements at other areas around the rear wheel well, there was about 1/2" extra clearance (12mm) over the radius rod bolt head. Like I said earlier, with a 1" drop I think you would be fine. Any more you might have issues.


"I wish I could get my car on a rack and get under it to make some measurements (lowered car with camber arms). I think measuring clearances with a tire installed maybe a little more accurate."

I did fit my 10" rim with the really high offset (+70mm) on the car and measured it with the car on the ground. I still has 3/16" clear on the radius rod bolt.

 

Here are photos of the widened rims that I had mentioned. These were a stock 7" wide 2004 G35 sedan sport rim that were widened by cutting 4 rims to make 2. About 3" was added to the inside of the rim only so this would be ALL positive offset added to the stock offset of the wheel. Total width is about 10" and the tire is a 275 width. Even with 3" added to the inside if the rim they still clear...barely. This is why I believe a higher offset can be used to get a wider rim/tire on these cars than anyone thinks will fit. These rims are around a +70 offset.

 

Amazing So a 10" wide +70mm with a 275 will fit!

So to get the same inside clearance with a 285, you would need to shift outboard by 1/2" (12.7mm) making the offset -57.3mm, so I guess you rounded down to +55mm.

What are your thoughts about 285 on 10.5 in then?

 

A +70mm offset appears to be the absolute maximum clearance on the inside suspension.

I figured out that with a 285 tire (11.2" tread width) on a 10" rim you would have 3/8" (10mm) on the inside clearance and 3/16" (4.5mm) sticking out past the edge of the fender. This should of course tuck as the vehicle suspension moves upward.

With a total clear space of just under 11.5" from radius bolt out to the fender edge, I don't see why a 10.5" rim would not work. If you had some real nuts you could try an 11" rim with a 285.

 

OK I know the newer ones are not the exact same but very close. I was looking into doing a 10.5" rear on my sedan and it will fit. It would be a +47 and will stick out about 1.4mm further than the Sevas I had. I would bet it can be done but you will need at least that offset or higher. Also you will want to be nice and low or they will stick out further and look like crap.

 

Yikes! That is WAAAY too close to the chassis components for me!

All you need is one good fender bender tap from the side and you got more than exterior sheet metal damage to worry about!

 

So don't crash.

 

Pan head bolts for the extremists?

 

Panheads = 11" rear rims.

 

It's not crashing that I'm worried about. It's Mrs. Momwiththeminivan that talks on her cell phone and tries to scold her kids in the backseat while driving that could t-bone me or swerve into my lane that worries me. I don't know about you but I haven't found a way of controlling that element of my everyday driving sklls yet.

With those clearances, it looks like it would be a whole lot of fun trying to get the wheel thats mashed into the control arms and chassis parts off of the car.

But hey, at least the 10's would have looked good before it molded into one with the car.