Wheels and Tires All things related to Miata Wheels and Tires.
Sponsored by:
Sponsored by:

wheel/tire opinions for 300whp NA

 
Old 12-11-2017, 04:50 PM
  #1  
Senior Member
Thread Starter
 
Join Date: Jun 2015
Location: TAMPA, FL
Posts: 787
Total Cats: 18
Default wheel/tire opinions for 300whp NA

Option 1: 15x10 w/ 245/40/15
Option 2: 15x9 w/ 225/45/15

Assume RS-4s or something similar. Going to be running XIDA ACE GS with no drop spindles. This is mostly a street car.

Is it possible to run 15x10 with 245 width tires on an NA miata and actually drive the car like a miata? IE- drive over bumps and turn the steering wheel without rubbing. I realize that 245 requires a fender pull. I think 225 does too. I'm willing to do this, but I've heard rumors of people pulling the fenders on their NA and still rubbing, which seems to me like a huge pain in the ***.

How noticeable of a difference between 225 and 245 width tires in terms of:
-grip when accelerating
-cornering grip?
-aerodynamic drag?
-hassle

Last edited by AlwaysBroken; 05-18-2018 at 07:47 PM.
AlwaysBroken is offline  
Old 12-11-2017, 04:54 PM
  #2  
Senior Member
 
matrussell122's Avatar
 
Join Date: Sep 2016
Location: Seattle
Posts: 1,215
Total Cats: 183
Default

Im running 15x9 245/40-15 RS-4's with a mild fender roll and I clear just fine. I removed the inner fenders too. Grip on the 245 RS4 is really good for a street tire and im happy with them. At full lock i barley rub on the sway bar but thats only when i pull out of my driveway.

Last edited by matrussell122; 12-11-2017 at 10:44 PM. Reason: added wheel size
matrussell122 is online now  
Old 12-11-2017, 05:33 PM
  #3  
Senior Member
 
Join Date: Feb 2007
Location: Aliso Viejo, CA
Posts: 1,087
Total Cats: 367
Default

Define "fit"
At 949 Racing, if it won't clear a damper sweep with the spring removed, it doesn't "fit". 15x8" fits.
If it just touches the inner wells or fender at full bump, we'd call that a race fitment and accept the minor rubbing as a compromise.
The 9" is a race fitment, as it rubs the swaybar and fender liners on both NA and NB.
The 10" has the same inboard obstacles, but adds interference with the fender that is manageable on the NB with a flat roll and aggressive alignment. NA's need a very hefty pull to get the wheel to clear the fender under bump travel. I've only seen 1 or 2 examples that have proven clearance at near full bump travel. One was my own NA with 245 Maxxis and rear fenders I took a sledgehammer to from the back side, not pretty.

If it's just a street car, or you're a novice/casual track driver, or your 3 piece shocks are missing a bunch of bump travel when compared to Xidas, you may never have the serious interference/rubbing that is possible under extreme bump travel.

This gets even trickier as the control arms pull the wheel in as you lower the car. Xida ACE and XL ride height ranges put the control arms roughly parallel to the ground, making for the worst case scenario for fitting wide wheels inside the fenders. Going below 5.5" pinch starts to bring the control arms past parallel and creates easier wheel fitment by pulling the wheel inboard and adding more negative camber, both static and dynamic. The dynamic part is important to prevent serious outboard rubbing.

Things are tight enough that the specific alignment and model of tire become noteworthy. Maxxis 245s run narrow and are "easy" to fit. The Hankook RS4 is a bit wider than the Maxxis, the BFG Rival even wider again with it's giant shoulder blocks.
doward is offline  
Old 12-11-2017, 05:38 PM
  #4  
Senior Member
 
Join Date: Feb 2007
Location: Aliso Viejo, CA
Posts: 1,087
Total Cats: 367
Default

Originally Posted by AlwaysBroken View Post
Option 1: 15x10 w/ 245/40/15
Option 2: 15x9 w/ 225/45/15

How noticeable of a difference between 225 and 245 width tires in terms of:
-grip when accelerating
-cornering grip?
-aerodynamic drag?
-hassle
Option 3: 15x9 w/245/40/15
Accelerates and brakes better than 225/9" because of bigger contact patch.
Easier to fit(hassle)
Is aerodynamic drag a serious concern?
More cornering grip than 225/9", less than 245/10". Either way, probably not noticeable on the street.
doward is offline  
Old 12-11-2017, 10:35 PM
  #5  
Senior Member
 
Join Date: May 2008
Location: Canada
Posts: 823
Total Cats: 473
Default

I've heard arguments on both sides regarding contact patch size, but my understanding is that size/area mostly depends upon tires pressures and vehicle weight (the idea being that tires are imperfect balloons). In other words, a 205/50-15 will have a longer/narrower contact patch than a 245/45-15 (but total area is approx. the same). This will vary due to wheel width, tire construction and moon phase, but as a rule-of-thumb, it should hold true. If you accept this, consider that tire compound will play a far larger role in providing straight-line traction than going to gonzo wheel and tire widths. Of course, if you're going for track performance in a high-po Miata, it's proven that the widest wheel/tire combination you can stuff under the fenders is the ticket.

Anecdotally, I've run sticky 205/50-R15s for many a year and have no trouble putting the power down (my situation is helped by having longer gearing than stock). Changing out my OEM BBS rims for 15x8 6ULs was a great upgrade, as it provided more than enough cornering stability for the street and didn't cause any tramlining issues. For track use, I switched to 15x9s with 225/45-15s. Last summer I used the larger wheel/tires on the street and was less happy. Yes, cornering was more effortless but it came at the cost of noticeably more rotating mass and a predilection to follow ruts in the road. YMMV.
DeerHunter is offline  
Old 12-12-2017, 02:34 PM
  #6  
Junior Member
 
Join Date: Feb 2016
Location: Panama City Beach, FL
Posts: 101
Total Cats: 24
Default

I think the part you are missing is that you are probably going to run lower pressures on the wider tire.
MrJon is offline  
Old 12-12-2017, 02:50 PM
  #7  
Senior Member
 
Join Date: May 2008
Location: Canada
Posts: 823
Total Cats: 473
Default

You can run lower pressures on a narrow tire (old drag racing trick). It's all a series of trade-offs. Do you want the best cornering ability? Run the wide tires and deal with the tramlining and reduced squirtability (the extra rotating mass makes the car less responsive). Do you want a car that's comfortable in the daily grind but still able to hold its own in the twisties? Run a narrower tire on a wide rim. My point is that the wider tire won't put down the power any better in a straight line - you'll have as much traction as your tire compound/pavement grip will allow.
DeerHunter is offline  
Old 12-12-2017, 03:57 PM
  #8  
Senior Member
Thread Starter
 
Join Date: Jun 2015
Location: TAMPA, FL
Posts: 787
Total Cats: 18
Default

I don't really care about removing fender liners or rolling/pulling the fender. If that's what I need to do for a significant upgrade in traction, then I'll do it.

But is this enough? Googling the various forums on this subject reveals a range of experiences from "I run 275 hoosiers on 15x9 on my 90 with no problems" to "I rub with 205 width tires on 15x7 wheels in my 99" But it seems like some people are possibly bitching about rubbing against the stock fender liners and some people are "fine" because they've pulled fenders and learned to live with not going full lock to keep the swaybar happy (which is honestly not a huge problem, depending upon how much steering wheel travel I'm giving up).

If it just touches the inner wells or fender at full bump, we'd call that a race fitment and accept the minor rubbing as a compromise.
I would be ok with this I think. Then again, I don't know how often I'm on the bumpstops. I would imagine fairly rarely during street driving, not sure about track use.
AlwaysBroken is offline  
Old 12-12-2017, 06:59 PM
  #9  
Elite Member
iTrader: (17)
 
Join Date: Aug 2007
Location: Knoxville, TN
Posts: 2,903
Total Cats: 171
Default

Height has a lot to do with rubbing as well, even to the point where you rub the top of the wheel well, where wheel fitment is basically irrelevant. I think that explains a lot of where the wide range of answers.

I've run a bunch of 225's on a 15x8 +25 on 2 NA's and 2 NB's with a light roll and I've been really happy with the setup for a street car. It's never rubbed at any reasonable height and until this recent cold front and some aging tires it hooked up in 2nd gear. I know 225's on a 8" wheel are a sin on here worthy of 400 neg cats, but anyone outside of the miata world thinks it's a completely reasonable option and I've been happy with it.
pdexta is offline  
Old 12-12-2017, 11:54 PM
  #10  
Elite Member
iTrader: (2)
 
Join Date: Aug 2016
Location: Woostuh, MA
Posts: 3,838
Total Cats: 102
Default

Originally Posted by pdexta View Post
Height has a lot to do with rubbing as well, even to the point where you rub the top of the wheel well, where wheel fitment is basically irrelevant. I think that explains a lot of where the wide range of answers.

I've run a bunch of 225's on a 15x8 +25 on 2 NA's and 2 NB's with a light roll and I've been really happy with the setup for a street car. It's never rubbed at any reasonable height and until this recent cold front and some aging tires it hooked up in 2nd gear. I know 225's on a 8" wheel are a sin on here worthy of 400 neg cats, but anyone outside of the miata world thinks it's a completely reasonable option and I've been happy with it.
A few folks on here run 225's on 8's and 245's on 9's as well!
ridethecliche is offline  
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
zumin
Meet and Greet
33
07-02-2012 10:35 AM
thesnowboarder
Engine Performance
31
03-09-2010 01:49 AM
naarleven
Media
9
10-07-2009 03:02 PM


Thread Tools
Search this Thread
Quick Reply: wheel/tire opinions for 300whp NA


Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.