Need Help Before I Place My APEX ARC-8 Order

[///BYU]

Hello All,

I could use your help before I place my order for the APEX ARC-8 group buy. Here's what I'm looking at:

18x9.5” ET35 square setup
18x9.5” ET22 square setup

My situation is as follows:

• Stock 1M, daily driver
• Plans for 1-3 track days a year
• Plans to mount Michelin PSS 255/40R18 at all four corners. If that proves to be too narrow I'll move up to 265/40R18. I'm more interested in having the "right" amount of traction vs. having the most traction possible (I know for some of you it's the same thing, but hopefully you'll understand what I'm talking about).

With either setup, rubbing should not be an issue. This is a question about suspension and chassis geometry.

I'm keen to maintain the stock 1M geometry as much as possible. In particular, the wheel/tire centerline so there is no change to the width of the track, scrub radius (does anyone remember that thread awhile back? ), etc. I know the tire diameters will change slightly because of the 18" size and the square setup, but other than that, I'd like to make it so nothing else changes.

The 18x9.5” ET35 wheels with a 5mm spacer in the front and a 12mm spacer in the rear make it so there is almost no change to the wheel/tire centerline. The front wheels move to the outside 1mm each and the rear wheels move to the outside 2mm each. The only problem (if it is a problem) - spacers are needed.

The 18x9.5" ET22 wheels move the wheel/tire centerline 9mm to the outside in the front and 3mm to the outside in the rear. When you add the front wheels together, the track becomes 18mm wider (0.71 inches) than stock. I know people will say wider is better, but I'd rather not mess with a good thing.

So which is better for my situation - maintaining the stock geometry (almost), but having to use spacers, or moving the wheels to the outside a little and not using spacers? In particular, would there be any issues with running spacers at a track day?

Thanks for the help!

[Rhys Jones]

That diameter will likely rub on the vent at the front of the wheel housing.255/40- 18 should work but will increase your speedo error.I tracked my car on stock tires at Grattan and felt it could use more grip all round but esp the rear.If you want square and no rub I'd go 265/35-18 in toyo r888.
Harold at Hpashop.com sells those wheels and is probably your best authority. Contact him

[MDORPHN]

Originally Posted by Rhys Jones

That diameter will likely rub on the vent at the front of the wheel housing.255/40- 18 should work but will increase your speedo error.I tracked my car on stock tires at Grattan and felt it could use more grip all round but esp the rear.If you want square and no rub I'd go 265/35-18 in toyo r888.
Harold at Hpashop.com sells those wheels and is probably your best authority. Contact him

With enough camber, 265/40-18 may fit.

FWIW, I run 265/35-18 in front on track and have ordered some 275/35-18s in front (with 295/35-18 in back) for this season.

Neil

[Rhys Jones]

The larger diameter of these will raise your front roll center also changing the front end geometry and behavior.For your goals go with the 265/35-18 on front. Personally I'd prefer to maintain some stagger and get a little more width at the back.Our cars have neither run flats nor spare so I'm thinking buy a 3rd front wheel and tire as a spare for track and street. On road courses it's always one front tire that wears out first.

[///BYU]

You're right--265/35R18 would be a better fit than 265/40R18. That was a mistake on my part. Anyway, I have time to figure out my tire decision; I'm not really worried about that at this point.

What I could use help with is my question about the wheel offsets. I want to get the ARC-08 wheels in 18x9.5". The two offsets available are ET35 and ET22.

ET35: This what I'm leaning toward. With the help of spacers (5mm front and 12mm rear), I can get the wheels almost back to the exact OE centerline - within 1mm in front and 2mm rear. The only downside is that it requires spacers to make this correction, but I really like that I can pretty much get the wheels right back to where there are with the stock setup. I don't want to change the geometry any more than I already am by going to an 18" square setup.

ET22: The downside with this setup is that it pushes the wheel centerline out from the OE geometry, adding 0.7 inches of width in the front (9mm on each side). I know a lot of people like the fact that this wheel widens the front track, but it's still a change compared to the OE geometry.

Both setups have their pros and cons, I guess. It's just a matter of which square setup is best overall for what I'm trying to do.

[MDORPHN]

Speak to Joe at Apex and/or Harold at HP Autowerks.

They both are very helpful and know 1Ms well.

You might also consider 18 X 10 et 25.

Neil

[///BYU]

Originally Posted by MDORPHN

Speak to Joe at Apex and/or Harold at HP Autowerks.

They both are very helpful and know 1Ms well.

You might also consider 18 X 10 et 25.

Neil

Thanks, Neil. Will do. I have 18x10" ET25 on my list, as well. It actually makes for very good fitment (perfect match to OE in the rear and pushes the centerline out only 6mm on each side in the front). I just don't know if I want my front wheels that wide. It would kind of limit me to 265s (I guess I could do 255s but they'd be pretty stretched--like my 255 winter tires on the OE rear wheels).

[HP Autosport]

Originally Posted by Rhys Jones

That diameter will likely rub on the vent at the front of the wheel housing.255/40- 18 should work but will increase your speedo error.I tracked my car on stock tires at Grattan and felt it could use more grip all round but esp the rear.If you want square and no rub I'd go 265/35-18 in toyo r888.
Harold at Hpashop.com sells those wheels and is probably your best authority. Contact him

Yes, too large, not width wise, but diameter wise!

35 series is the way to go in 245. 255 and 265 widths.

Originally Posted by ///BYU

You're right--265/35R18 would be a better fit than 265/40R18. That was a mistake on my part. Anyway, I have time to figure out my tire decision; I'm not really worried about that at this point.

What I could use help with is my question about the wheel offsets. I want to get the ARC-08 wheels in 18x9.5". The two offsets available are ET35 and ET22.

ET35: This what I'm leaning toward. With the help of spacers (5mm front and 12mm rear), I can get the wheels almost back to the exact OE centerline - within 1mm in front and 2mm rear. The only downside is that it requires spacers to make this correction, but I really like that I can pretty much get the wheels right back to where there are with the stock setup. I don't want to change the geometry any more than I already am by going to an 18" square setup.

ET22: The downside with this setup is that it pushes the wheel centerline out from the OE geometry, adding 0.7 inches of width in the front (9mm on each side). I know a lot of people like the fact that this wheel widens the front track, but it's still a change compared to the OE geometry.

Both setups have their pros and cons, I guess. It's just a matter of which square setup is best overall for what I'm trying to do.

You just answered your own question with regards to offset.

[///BYU]

Thanks, Harold. I appreciate the help. :)