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That would entail several other mods too body wise
About offset, stock wheel has +50 mm That is about 2 inches
So if an 8 inch wheel has that offset, the backspacing should be 6 inches behind the hub
2 inches upfront So on a 10 inch wheel for ie, I would need have no more than 6 in backspace or else it would not fit (also depending on tire aspect ratio )
With sinilar aspect ratio then I would like having 6 in backspace So I'd have 4 in upfront
Heard and read some going for less offset Why ? Anyone looking for a 10 in wide wheel with less offset should go for an 11 in wheel with stock *50 offset right?
9.5 or 10 or 10.5 or even 11 in wheels in +50 ate hard to get ?
You want to stick around the +50mm offset for scrub radius and the way the suspension is designed.
You want to center the wheel into the wheel well and stay around the stock scrub radius. If you can satisfy all these requirements you will get the best handling as per design of the car.
You only have so much room to go inward, an 11" +50mm will not fit because it will contact the suspension. so you have some options, you either get suspension that has a smaller diameter, run a less wide wheel, or push the wheel outward with a lower offset. Since lower offsets don't ride as well (they tend to pull the car left and right with road irregularities and put different loads on the wheel bearings and suspension, etc, etc I recommend sticking close to the stock offset.
so the tested fitments that are known to work are 18x9.5 +45mm and I think you can go to a 18x11 +45mm but won't get the full lock to lock movement as the wheel does contact the suspension a little at full lock. so a good compromise is probably a 18x10 +50mm if you can find it, or just run a 18x9.5 +45 with a 245/40/18 tire which is what I settled on. this requires no fender modifications and also gets you full turning without rubbing and another huge positive is the 245/40/18 tires are a lot cheaper than anything wider. its the best value to width in the 18" size along with a very close tire OD to stock.
I went all out with my FD rx7 and went with a +43mm 18x11.5" and rolled the fenders and have small coilover springs and run a stretched 285/30/18 tire. It does have more grip when heated up and takes a little more heat to warm them up. This car is also a lot faster in terms of WHP. I am running the larger 99 spec brakes and ohlins DFV on that car with softer rate springs 8/6.
comparing the two, I would opt for the easier fitment of 18x9.5 +45 and if you want more grip step up to a higher grip tire unless you want to go all out with fender rolling and custom wheels.
If a +50 mm (about 2 in) offset on a stock 18 X 8 wheel delivers a backspace of 6 in, being the center of a 18 X 8 wheel the 4 in mark, ( hence moving the mounting point of the wheel 2 in out wards from center point, delivering 6 in behind hub - 6 in backspace and 2 inches on front of hub ) then, in that case, a 18 X 10 in wheel for ie. would have its center pointat the 5 in mark
So on this 18 X 10 wheel on this example, having a + 50mm offset (about 2 in away from center point of wheel to the outside of vehicle-hub ) would deliver the mounting point with 7 in backspacing, 7 inches of wheel behind the hub , and 3 inches before the hub, outside side of wheel
That would give us 7 inches of backspacing versus 6 inches the stock wheel has
Not good
So if I want to keep the stock 6 inches of backspacing in an 18 X 10 wheel , I would need less than +50 mm offset
If 50 mm is about 2 inches and 2 inches offset leaves 7 inches of backspacing on the 10 in wide wheel, then half that amount of offset (50mm X 1/2 = 1 in or 25mm) would leave me with a desired backspace number of 6 inches, and 4 inches of wheel up front, towards the outside of vehicle, before hub
Would that be correct ? 18X 10 +25mm 6 in backspace .
Anything higher than 25mm offset on a 10 inch wheel would add to stock backspacing
A 9.5 inch wheel with +50 offset would have more than 6 inches of backspacing
For instance a 12 inch wide wheel would need zero (0) offset to have 6 inches backspacing Anything more than zero would send more than 6 inches inside the wheel well
My car is running on Koni double adjustable. And its adjusted to F 5" R 4.75". (Negative Rake).
Car drives great. But I wish I can get more front camber. Tire wear and temperatures show that I could benefit from it.
If a +50 mm (about 2 in) offset on a stock 18 X 8 wheel delivers a backspace of 6 in, being the center of a 18 X 8 wheel the 4 in mark, ( hence moving the mounting point of the wheel 2 in out wards from center point, delivering 6 in behind hub - 6 in backspace and 2 inches on front of hub ) then, in that case, a 18 X 10 in wheel for ie. would have its center pointat the 5 in mark
So on this 18 X 10 wheel on this example, having a + 50mm offset (about 2 in away from center point of wheel to the outside of vehicle-hub ) would deliver the mounting point with 7 in backspacing, 7 inches of wheel behind the hub , and 3 inches before the hub, outside side of wheel
That would give us 7 inches of backspacing versus 6 inches the stock wheel has
Not good
So if I want to keep the stock 6 inches of backspacing in an 18 X 10 wheel , I would need less than +50 mm offset
If 50 mm is about 2 inches and 2 inches offset leaves 7 inches of backspacing on the 10 in wide wheel, then half that amount of offset (50mm X 1/2 = 1 in or 25mm) would leave me with a desired backspace number of 6 inches, and 4 inches of wheel up front, towards the outside of vehicle, before hub
Would that be correct ? 18X 10 +25mm 6 in backspace .
Anything higher than 25mm offset on a 10 inch wheel would add to stock backspacing
A 9.5 inch wheel with +50 offset would have more than 6 inches of backspacing
For instance a 12 inch wide wheel would need zero (0) offset to have 6 inches backspacing Anything more than zero would send more than 6 inches inside the wheel well
a wider wheel with the same offset of stock will get closer to the suspension. yes.
You do have some room to move towards the suspension. so rather than racking your brain over where the exact location is from the hub of the suspension, I would go with proven solutions.
we know a 18x10 +45 or +50 fits. so no math needed but on a 18x10 +50 you are getting really close to the suspension. You will also need to run a tire that isn't overly large as if the tire sticks way out you can contact the suspension on full lock turning, and even if you do its not the end of the world.
I know someone here has run a 18x11 +45mm and he does get a little contact at full wheel lock.
But I suggest going with a 18x10.5 +47mm PF01, storeoutperformance is the place that sells this special offset if you want max performance. you may have a little rubbing at full wheel lock when turning but that is ok and you will probably need to roll the fenders. Run a sticky 265/275 35 18 tire and the car should really stick. I got my 18x9.5 +45 for a really good deal so I am running them, I also got my RS-3 tires in 245/40/18 for a little over $100 each so it was affordable. You can find some enkei rpf1 18x9.5 +45mm for a little over $1K new, those I think look pretty good as well and are light and strong and needs no fender modification perfect to run those with a 245/40/18. The decision is up to you.
Keep in mind that driver ability is worth so much that this isn't going to overcome how much the driver matters. it adds some more grip and will be faster overall though.
Will settle for 10 in wheels From what I read 9.5 to 10 is a good no issues size
18 X 10 +50 to + 47
I like and want as much tire & wheel as possible inside fender well
As much positive offset as posible Hate wimpy wheels with low offset that protrude the fender openings but have no substance
Function is also super important hence no 19 or over diameters
For outocross will use my stock wheels or would like finding 17 X 10 That is my next quest 17 X 10 with an offset that works with competition rubber For that matter 45-40 aspect ratio
a 17x10 with 255/40/17 is a good size, it will have a smaller diameter tire than stock but it would work well on that wheel width. We run that width a lot on rx7's.
I recently went through all this with my rx8...deciding on wheels that is. I went with 18x9.5 cause they are easy to find used. if you look at tires 245/40/18 tires are much cheaper on average than wider tires in 18's.
Another tire I would like to try is the federal FZ-201. looks like a fun tire to run, too bad all the sizes have smaller than the stock OD.
Check this out A 255-45-18 is only slightly larger in diameter, unnoticeable when conpared to the 255-40 size
With a 17X 10 wheel A better size for autocross More stiff sidewall is better than a low sidewall
Not bad at all
Only slightly larger but wider as well
17x10 is a great track wheel size IMHO.
What other mods do you have for autox?
17x10 will put you on a modified or prepared class.
If you are not interested in scca classing, it makes no difference.
We used to drive on STX, so 9" and 200TWR was the limit.
Yes definitely that size sounds good fun autocross
So far my car is stock except for suspension which is Ohlins and Racing Beat sway bars
Definitely got to go to Willow Springs and start getting into some driving time
This suspension is great, and inviting, got to watch out !
Want no tickets ! But I am cool, do no stupid things on the road
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Ohlins DFV is my preferred choice. Fantastic suspension after you set it up.
I have a little stiffer sway bars than those. Just a personal preference
In use the 9" wheels because I already got them from the AutoX STX set up, but If i can choose again, I will get 9.5 or 10" for the track.
However, I had not being able to use the full tire width on track yet, based on temperatures and wear. I need more camber. I should correct that before next event and test.
I imagine that you might not have the same issues because of your choice of sway bars and springs rates.
But a few weeks back I began to notice a clunking noise in the front that is getting more prevalent, upon going over speed bumps, rough terrain, and at low speeds.
That meaning highway driving is silent. Checked it out at a friends shop lifting the car up.
Everything looks solid, sway bars, suspension mounting points, nothing lose. Guys at shop tell me it seems internal, inside struts.
Called Ohlins. Jake told me to check mounting hat, make sure it is tight. Check sway bar all around.
It all seems tight.
From installation all seemed good. After about 2 months of driving it came apparent. It did not sound from the start.
Nothing will fall off, so I will keep monitoring the situation.
Ohlins tells me I can always send them the parts for assessment.
Will see.
Anyone had any experiences like this before ?
About rear suspension, would like to add camber adjustment, to prevent premature tire wear.
I had a clunking noise coming from the front suspension. Turned out it was the top mounting nut for one of the front struts. It came off and the Koni proceeded to destroy itself by bashing the adjuster into the frame. That how I wound up with Ohlins.
Point being: Have you actually put a wrench on the nuts/bolts and made sure they are torqued to spec?
I wish all the moderators who respond and/or read this thread would recognize that there's a dedicated suspension forum area and this 8 month long thread isn't posted there ... sigh ...