JScheier

Hmmm... I see Porsche and Corvettes coming out of the factory OEM with huge rear tires and smaller front tires... aka staggered setup. Pretty sure these are world-class cars that don't under steer terribly. Must be that the spring rates are adjusted to compensate for that.

Square setup, drop the rear rate or increase the front rate. Appears that an adjustable sway bar will do the trick on either end (as evidenced by several of us running square setups).

<or> just drive the car as delivered and enjoy the heck out of it.

SD GT

Yes.
PM inbound

908ssp

Actually the Porsche had horrible oversteer problems with same size tires front and rear do to the rear engine. The Corvette has a transaxle and 50/50 weight distribution so it can get away with larger rear tires as well. Our cars can be made to handle very well with larger tires in the back. A stiffer rear sway bar in the back will load the front more and pull up on the outside rear tire putting more load on the front canceling some of the understeer. But for absolute maximum G loads you would want the widest tire you can on all four wheels.

Krnnerdboy

Interesting! I always thought the stiffer sway bar would make that axle lose grip instead of giving the opposing axle more grip....thanks!

OLOABoss

And you would be correct. Adding more front rubber would nessitate a bigger front bar or smaller rear bar.

Peter

JScheier

Just as an update, Vorshlag has mounted 315s on the D-Force 18x10s and test fit them. Take a look HERE

nota4re

I spent quite a bit of time chatting with the D-Force guys at SEMA. First class people, extremely knowledgeable, great business people. I have no doubt they will bring a quality product to us and they will stand behind it. I wish them the very best!

POS VETT

Any chance for an 18x11 version ?

adam81

Sounds like they barely fit..... Would you be comfortable running these on high speed road courses? It sounds like they MAY be okay for autocross only.....????

JScheier

The 315 is pinched some on the 10" wheel, but fits.

The wheel & tire combo have plenty of clearance to the strut and the fender for coil-over cars running camber (OEM perches will most likely not be an option). Looks like the rear is a non-issue (we already kind of knew that).

Personally, since I run time-trails and depend on modification points staying low, I'll stick with a 295 or 285 series tires to not incur points and/or actually loose a point (TTA size is 295) where I can.

For Auto-x, this one is a no-brainer. You want the most grip you can squeeze under the OEM fender.

adam81

Got it. What I was getting at, in form of a question because I don't know, is even though the tire fits can it still become a safety issue? To put it into an analogy: I could squeeze into a tiny coat. But the moment I started moving around I would probably rip it....

iDrive

There are several of us running 315's on 18 x 10 and 10.5 for a couple years now. Sam also used the factory perches on his AST's with a 5mm spacer without rubbing. The 315 rears, unknown to Fair yet, slightly rub on the rear sway bar (tire sidwall flex). At least on Hoosiers with a 18 x 10.5, 38mm offset, and one of Sam's rear bars. I'm not sure what offset the D-Force 18 x 10 is or the width of the 315 Kumho, but it has the same inside gap in Fair's photo as my set-up.

Dave

JScheier

Good info Dave!

Adam - Not really a safety issue. As Dave has mentioned, auto-xrs do this constantly (look at what they used to cram onto the 7.5" and 8" wheels!). For track days, you have to look at the trade-off between grip, slip and drag.