15x8 vs 15x9 wheels / tires

[zev]

Hey All,

 

I currently run 15x8 Rota RKR's (0 offset) on my 72 Z. There was a small amount of rubbing front and back but I rolled the front and rear fenders VERY slightly and now they don't rub, but only just don't rub so it's pretty close.

 

The problem is I just can't stand the look of the zero offset wheel so I'd like to swap these out, but I also hate the super stretched look. I don't mind a little stretch, but nothing crazy. Can anyone chime in about their experiences with a 15x9 -13 offset and tell me what tires you used and what the rubbing situation is like? Or any general advice here of what I might want to look at in terms of a wheel / tire package for a 15 inch rim?

 

Here's a pic of my current setup with the 15x8's 

 

Thanks!

 

 

[jhm]

If your 15x8, et0 wheels are almost rubbing on the outer fender sheet metal, then 15x9, -13 will definitely have major interference issues….negative offset will create a deeper “dish”.  Sounds like you may want to look at wheels with some positive offset, but be careful that they don’t have interference with the strut tubes on the inside (assuming that you’re running stock-diameter strut springs).
 

There are dozens of threads here on this exact topic; have you already reviewed them and not found a suitable solution?

[zev]

9 minutes ago, jhm said:

If your 15x8, et0 wheels are almost rubbing on the outer fender sheet metal, then 15x9, -13 will definitely have major interference issues.  Sounds like you may want to look at wheels with some positive offset, but be careful that they don’t have interference with the strut tubes on the inside (assuming that you’re running stock-diameter strut springs).
 

There are dozens of threads here on this exact topic; have you already reviewed them and not found a suitable solution?

Thanks for the reply. I feel like I’ve been reading so many forum posts on this topic that I am about to go blind. 
 

If I look at wheels with positive offset that won’t give me the deep dish look though, since it would move the spokes even further towards the outside of the wheel, right?

 

I guess the answer is that I just need to roll the fenders more to accommodate the negative offset. 
 

Does adding offset negatively impact handling for a street car?

 

[jhm]

Sorry, I may be misunderstanding what you’re trying to achieve.  Do you want a look that has a deeper dish or a shallower dish?  Positive offset gives you a shallower dish, which is what I thought you were hoping to achieve.  My bad if I misunderstood.

 

Sounds like you don’t want to go the route of fender flares, since you’re talking about rolling the fenders even more?

 

Regarding handling…offset (by itself) doesn’t really factor, unless it makes a difference in vehicle track width.  A wider track will generally improve a car’s stability and overall handling (assuming all other factors equal).  Negative offset can give you more room on the inside for bigger brakes.  Many of the OTS big brake kits on the market today advertise possible interference with 15” wheels and smaller.

 

Hope this helps.

[zev]

29 minutes ago, jhm said:

Sorry, I may be misunderstanding what you’re trying to achieve.  Do you want a look that has a deeper dish or a shallower dish?  Positive offset gives you a shallower dish, which is what I thought you were hoping to achieve.  My bad if I misunderstood.

 

Sounds like you don’t want to go the route of fender flares, since you’re talking about rolling the fenders even more?

 

Regarding handling…offset (by itself) doesn’t really factor, unless it makes a difference in vehicle track width.  A wider track will generally improve a car’s stability and overall handling (assuming all other factors equal).  Negative offset can give you more room on the inside for bigger brakes.  Many of the OTS big brake kits on the market today advertise possible interference with 15” wheels and smaller.

 

Hope this helps.

Exactly, I am hoping to achieve a slightly more deep dish look at the wheels which is why I am looking at a slight negative offset. 

[jhm]

Got it.  Something for your consideration…IMO, that style thick-spoke wheel often “appears” to have less offset (ie, shallower dish) than many other wheels designs of the same offset.  Unless you’re set on keeping those Rotas, you could consider a different wheel of zero offset and achieve that look you’re striving for.  Food for thought…

 

Another option to help with the fender clearance issue — more negative camber on all four corners.  

[madkaw]

I run 17x8.5 +4 offset . Not sure the offsets are a clear indicator of dish size . 
I’m going to run 235/45/17’s . I think it’s more about wheel design 

[clarkspeed]

There is only so much room to work with. If the inside is a 1/4" or so away from your strut, then the outside edge will fall where it may.  I usually shoot for 0 or a little interference on the inside and use a wheel spacer to compensate.  Can't give exact numbers because tire size and suspension travel make a big difference. Once you go to a 8+ rim without flares every 1/8" counts.

 

Best to remove spring and jack wheel through full travel. If you already have the Rotas mounted up, you should be able to predict what a change in offset or width will do for you.

[zev]

13 hours ago, clarkspeed said:

There is only so much room to work with. If the inside is a 1/4" or so away from your strut, then the outside edge will fall where it may.  I usually shoot for 0 or a little interference on the inside and use a wheel spacer to compensate.  Can't give exact numbers because tire size and suspension travel make a big difference. Once you go to a 8+ rim without flares every 1/8" counts.

 

Best to remove spring and jack wheel through full travel. If you already have the Rotas mounted up, you should be able to predict what a change in offset or width will do for you.

Thanks, that’s a great call. 

[Kennysgreen280zt]

I usually put wheel/offset/tire sizes into this calculator: https://www.willtheyfit.com

 

Stick the size you have now in there, and what sizes you're thinking about and you can visually/numerically see where they will move. Its been very helpful for me.

[Zetsaz]

You're gonna be out by an entire inch from where you are now.

 

More aggressive negative offset on top of the extra width is going to require flares or some pulling and rolling. The front fenders have a bit more clearance, but the rear will definitely be rubbing and the top of the wheel will be outside the body line unless you get some fairly aggressive negative camber.

 

I'm with jhm that's it's partially the style of the wheels that will determine the look of the dish 

 

You're near the limit of what you can do on a stock body with reasonably wide tires and camber.

[bruce83]

Here's a website that may help in deciding on wheel and tire fitment. https://www.wheel-size.com/calc/?wheel1=195-70-14X5ET15&wheel2=225-45-16X8ET19&wheel3=225-55-15X7.5ET15&wheel4=225-45-16X8ET19&wheel5=225-55-15X7.5ET15&wheel6=225-50-16X7.5ET15&fcl=50mm&wcl=30mm&scl=50mm&sr=0mm I have already set it up for you 72' 240Z and the OEM is on the left side and 16x9 with 13 offset on the right. You can change all of the right side amounts to see how they will fit your car and see the tire clearance on non-modified fenders and OEM struts.

[Randall.K12]

On 7/23/2023 at 11:17 AM, zev said:

Hey All,

 

I currently run 15x8 Rota RKR's (0 offset) on my 72 Z. There was a small amount of rubbing front and back but I rolled the front and rear fenders VERY slightly and now they don't rub, but only just don't rub so it's pretty close.

 

The problem is I just can't stand the look of the zero offset wheel so I'd like to swap these out, but I also hate the super stretched look. I don't mind a little stretch, but nothing crazy. Can anyone chime in about their experiences with a 15x9 -13 offset and tell me what tires you used and what the rubbing situation is like? Or any general advice here of what I might want to look at in terms of a wheel / tire package for a 15 inch rim?

 

Here's a pic of my current setup with the 15x8's 

 

Thanks!

 

 

Hi, will echo the other responses about difficulty fitting that size wheel.  With a 15/9 and -13 offset, you will have about 5/8” of poke, which would probably require a pretty decent stretch and roll to squeeze under the fender.  I think you’d be nearly flush with a 15x8 -13.

 

I am running 15x9” wheels with -03 offset.  Tires are 205/55 and I’m on coilovers.  There is zero rubbing lock to lock without rolled fenders.  I think I could get away with 215/55 next time around.

 

Food for thought.  Good luck with your research.

[Michael]

At the risk of being a crusty curmudgeon, what's the advantage of going all of the way to a 15x9 wheel, while limiting the tire series to 205 or 215?  Currently I run 15x7 wheels, with 225-series tires... looks to be a decent match, both geometrically and aesthetically.  

 

With a 15x9 wheel, wouldn't it make more sense, to install something like a 275/50 tire?  Like Hoosier R7, which is one of the few tires available in that size?

[zev]

Thanks all! I think based on the feedback here I will just stick with my 15x8 wheels and 225/50/15 tires instead of trying to punch out to a bigger size. Seems like the general consensus is that the offset won’t works, so I’ll stick to what’s tried and true 

[calZ]

On 9/4/2023 at 12:51 PM, Michael said:

At the risk of being a crusty curmudgeon, what's the advantage of going all of the way to a 15x9 wheel, while limiting the tire series to 205 or 215?  Currently I run 15x7 wheels, with 225-series tires... looks to be a decent match, both geometrically and aesthetically.  

 

With a 15x9 wheel, wouldn't it make more sense, to install something like a 275/50 tire?  Like Hoosier R7, which is one of the few tires available in that size?

 A 9" with a 205 is too far imo, but a small amount of stretch has been proven to increase grip. Bulging sidewalls make the tire mushy.