Just a quick question. I need some more rear negative camber to fit the rear wheels more to my liking. Already have about -4ish. Pbm coilovers, everything else is stock. Any suggestions?

I got some new wheels recently RPF1's 17x9 +45

They currently have 245/40 all around. I like the look of a wider tire. Wondering if I can clear the outside front fender with 265/40. Stock suspension.

I searched the archives and used that spreadsheet calculator. Using 255's leaves 0.27" clearance. Add 5mm or 0.2" of tire and you're left with 0.07" from the outside fender. Will this mean i'll potentially rub the fender/liner or rub the liner bolt on hard cornering?

Edit: I also run -1.2deg of camber up front

+1 but with 18's.I'm about to change my set up and want to run 265's aswell.

a 265/40 tire in the front IMO is very tall and will look goofy, not to mention a 265 tire will balloon a bit on a 9 inch rim.

I wouldn't go any wider than a 255/40 in the front, 265/40 rear would be 'ok.'

All depends on what you're going for.

I like a slight bulge which is why I was looking at the 265's. Not much tire choices though so I'll probably just stay with a stickier 255 as most recommend.

Cheers

you could run 275 rears on 9", that's at the limit though.
FWIW, I'm running 255/40-17 fronts and 275/40-17 rears on 8.5 + 40 and 9.5 +40 NT01s, no problem with rolled stock fenders at 25" max height of fender opening (maybe a little lower than that up front).

Not a fan of staggered setup. Like to keep it square for rotating purposes.

So 18x9.5 +38 Will fit a with a roll up front? with some camber? Im ok on just down springs because the offset is pushing out instead of in correct?

tire size 255 or 265? I doubt I'd notice a difference in with really.

you want to fit the tire onto the wheel with a slight stretch. 235/40/18 or 245/35/18 are the tire choices you want.

the 245/35/18 and the shorter tire diameter is a better fit.

That seems like more than a little stretch. Stock is 225 on an 8" wheel. I don't really like the stretched look, but I do realize it's better for performance, but to a point I would think. 265 is the recommended size from tire rack etc, so that's 30mm or about 1 1/4" narrower than the recommended. Is the narrower tire just to get the wheel to fit, or is it actually better? I'll just get another wheel if it's just to get it to fit. I want a square setup and 235 in the back doesn't seem like much of an improvement. Thanks for anymore info, I appreciate it.

It's actually better.


you want to run the widest wheel you can front and rear, and then fit the tire onto the wheel with a slight stretch. Race cars do this because it puts the tire under tension, its basically "locks" the tread into place and the tread does not move or fold over. The optimal performance set up is when the wheel width is wider than the tread width which creates the favorable slightly stretched set up which locks the tread pattern into place. this is obviously for performance, and not for comfort. Tirerack and tire manufacturers recommend a mix of performance and handling, I am taking it to the extreme for performance, all racing does this.

Thanks for the explanation.

I just went through all the pages and didn't find the exact set up that I came across.I found a set of rims that I would love to buy.The thing is they are in clearance and only 1 set is available.

18x9 +25
18x10+30

Tires I'm not sure what to run but first I would like to know if those offsets will fit.Stock body by the way.Thanks for the help!

This doesn't mean that 235 or 245 is going to perform better than 255 or 265 (or 275) on a 9.5" wheel. My money would be on the wider tires for max lateral grip.

That said, with rolled fenders, 255/35-18 will fit up front on +38 offset, 265 maybe not... Could run 275 rears if desired, ability to rotate is overrated IMO...

And you'd win money. I don't know why people keep perpetuating the myth that a stretched tire feels better and is therefore faster.

EXACTLY!

You want to run the widest wheels with the widest tires possible. The thought that a 235/40 will be faster than a 255 or 265 on a 9.5in wheel is ridiculous. I really wish people like lOOkatme would stop perpetuating this myth.

A 255 is faster than a 235 on a 9.5. Run the 255.

We already know that at 235 is faster on a wider wheel...guess what! A 255 is even faster than a 235 on a wider wheel!

And you'd win money. I don't know why people keep perpetuating the myth that a stretched tire feels better and is therefore faster.

EXACTLY!

You want to run the widest wheels with the widest tires possible. The thought that a 235/40 will be faster than a 255 or 265 on a 9.5in wheel is ridiculous. I really wish people like lOOkatme would stop perpetuating this myth.

A 255 is faster than a 235 on a 9.5. Run the 255.

We already know that at 235 is faster on a wider wheel...guess what! A 255 is even faster than a 235 on a wider wheel!

Yes, but there are also many people perpetuating another myth that a wide tire on a narrower wheel is going to be faster than that same wide tire on a wider wheel.

THIS is the misperception that LOOKatme is rightfully fighting against.

We have known that a 285/295 fits a fairly stock fendered FD for over a decade, and during that time most people were fairly happy running a 10" wide wheel.

Though that 285/295 tire may be as wide as can easily be fit, a wheel wider than 10" is easy to fit and real measurable performance benefits can be realized- not just feel.

On my set up I found the 18x11 +45 worked very well for me with the 295 I was running.

These were not the common "semi-cantilever" design of the Hoosier A6/A7, but rather the currently fastest time attack legal tire- Hankook Ventus TD Z221.

If we just keep repeating the old auto-x/track FD mantra of 285 on a 18x10 7.5BS
and try to adapt that to time attack we are going to be leaving a lot on the table.

Wot? I've never seen anyone suggest that.

By suggesting 235s and 245s for 9.5" wheels? In the "Maximum wheel and Tire Width Fitment Guide"?

What's being perpetuated is the absurd idea that you have to run a tire that has your wheel width as its MAXIMUM wheel width. "18x9.5" wheel? Hmmm, 235/40-18 and 245/35-18 both are OK because they have 9.5" as the max wheel width, but 255/35-18 can fit on a 10" max width so obviously you wouldn't want that, right?!"

Utter nonsense. 255/35-18 or 265/35-18 are better tire size choice for a 9.5" wheel on an FD than 235/40 or 245/35 for performance. And particularly for someone who explicitly stated: "I don't really like the stretched look"

One of the many Grassroots Motorsports tire tests found this a few years ago on an RX8.

The narrower of two of the same tire model on the same size wheel was significantly better (faster) than the wider tire.

It is a measurable difference.

I don't care if anyone pays attention to the facts or not, and really I prefer my competition to remain ignorant.

Currently I have 2 sets of Hoosier 285/30/18 A6's mounted on 2 different sets of wheels.

The first set is 18x9.5 and the other is 18x10.

When the wheels come off the car I will stack them all up, take a pick and you all can decide for yourselves which set puts more rubber on the road.

Your 18x11 +45 fitment is an excellent one, however people do need to understand that this is unconventional and not without complications. While you may consider my suggested fitments conservative, they are also tried and true and without strong complications. Is your 18x11 with 295 faster than the same tire on a 18x10? I don't doubt it.

There are a few complications with the fitment though...

1. It is difficult to maintain a 25i inch ride height. This comes with dynamic as well as aero compromises.
2. You will need to seriously roll your fenders probably more like pull your fenders.
3. You may need to run too much camber to fit the tires. This may be ok for Autox but may not be ideal for road racing which generally calls for less camber. This depends on what tires you are running and what kind of camber they like.

By suggesting 235s and 245s for 9.5" wheels? In the "Maximum wheel and Tire Width Fitment Guide"?

As I stated earlier in this thread there are many many posts that don't belong in this thread because people aren't looking for maximum wheel/tire fitment.

lOOkatme
you want to run the widest wheel you can front and rear, and then fit the tire onto the wheel with a slight stretch.

This is what he is really getting at.

I would rather say you want to run the widest tire you can fit and then the widest wheel that tire and your chassis can support.



Yes, please, lets stop talking about 235s, 255s or 265s and 8" and 9" wide wheels in this thread.

285 on 10" wide wheel with 7.5 Back Space is the over decade long yardstick F/R for stock/near stock body FD.

If you can't figure out how to fit a narrower wheel and or tire go research what offset and backspace is.

Lets keep pushing the limits of the FD!

There are a few complications with the fitment though...

18x11 +45 versus 18x10 7.5 Back Space basically comes down to you are running 5mm less offset or placing the tire 5mm further to just clear coilovers on the inside with the wider wheel.

Actual complications I ran into were-

had to shorten my Tripoint speedway style swaybar to get full steering lock.
had to pull my front fenders that 5mm from the previous roll as you state.
had to roll my still stock rear fender lips under.
had to increase my damping (should be spring) from extra wheel/tire weight/grip.
had to drive harder to find the limit of traction. :lol:


---------------
Ride height? If you mean from the larger diameter 295 vs 285 I see your (very small) point.

Camber- I have 2.4 deg up front and 1.2 in the rear, I can't see tracking with less camber. Most FD auto-xers are trying to double the camber I run.

Maybe in non-competitive track days.
--------------

I am not in any way trying tout my set up as an ultimate FD fitment- just another option.

I also want people to know what extra work they will have to put in to make it work and the disadvantages.

I definitely want more people to run the 18x11 +45 295 setup as well so they can note the advantages/spread the word/make faster FDs.

I think its awesome we can get light strong monoblock custom offset wide wheels for 1/2 the price of the old CCWs!

Linkie to test? What tire sizes? Were the wider tires also taller, affecting gearing? What kind of course? How many laps?

Wider but heavier (and often taller) tires can improve cornering while hurting lap times on relatively modest power/weight cars like the RX-8. R&T tested tires on an FR-S, and gained cornering grip with 235/40-18s vs. 215/45-17 StarSpec tires, but lap times were slower due to the additional rotational mass and effectively taller overall gearing.

I haven't seen anyone in this thread suggest that narrower wheels with the same tire size should perform better. Of course within reason the wider wheel will give superior performance.

But as to the question of what tire to run on a 9.5" wheel, again I would put my money on a 255 or 265 or 275 over a 235 or 245 as far as maximum lateral grip is concerned.

Just because an RX-8 went faster on narrower tires on a given wheel does not universally prove that narrower tires are "better" than wider on a given wheel width.

It was a stock class RX-8 and they were trying to stuff 285/30-18 on the stock 18x8 wheels.

Yes, tire weight and diameter can have a huge effect on a low power car as the weight is even further from the axis of rotation than a wheel.

That said, sometimes I wonder if the testers just need more time to adjust their driving style.

When I put my 18x11 295s on my stock auto RX-8 (dynoed 108rwhp) its fast at auto-x but you have to drive with incredible slip angle in the tight stuff to keep the rear tires spinning and speeds up. I mean, you look like a jackhole drifter at times sliding the 14.6ft long RX-8 through 15ft wide "Miata" lanes.

Well, the vague feeling of 285s A6s muffin topped onto 8" wide rim and trying to drive with high slip angle might be too much to expect even for the testers' expert driving... I don't envy that proposition.:icon_tdow

:lol:

So of course this proves that 235 is better on a 9.5" wheel than 255 :rofl:

Ha! Sounds fun, actually...

I dunno, could be fun to try, "interesting" at the very least :)

For the record, the minimum wheel width for a 285/30-18 is 9.5". Running a 285 on an 8" wheel is of course perfectly absurd and well outside what the tire was designed for.

Of course this GRM test doesn't even begin to prove superiority of 235/40-18 over 255/35-18 on a 9.5" wheel, which is what was being suggested.