295 front / 325 rear?

[guarnibl]

Do you guys happen to have an idea of what offset for 19's I will need to run front and rear for a 295 up front and a 325 out back on 19x10 (or 19x10.5) and 19x11.5 (while being able to drop the suspension) ? I'm running steel brakes. Not for track use, but I loved having wide front tires on my previously lowered RWD car. I'm planning on using the height adjustable KW springs so I can get between 15-35mm drop.

Planning on custom ordering wheels... car won't be here from ED for another 2 months. I looked at APEX, but couldn't find anything in 19x11.5... I know their 18's would work, but I was hoping to stick with 19's.... not a big fan of 18's on newer model cars... perhaps on an E46, but not on an E9X/F8X.

Stock wheels are 255/275 on 19x9 and 19x10... I guess I see now why Porsche puts a 305 on a 12" wheel. On my Boss 302, stock was 255 up front on a 9" wheel and 285 on a 9.5" wheel. I went to Forgestar's and ran a 295 (Toyo Proxes 1) up front on a 19x10, and a 325 (Toyo Proxes R888) out back on 19x11. The rear tire was slightly too large (per Tire Rack the min. width was 11.5"), but the car handled great since R888's have a rather stiff side wall. The Boss 302 is obviously quite different than the BMW... so not sure how tires/drop will adjust the handling of the car... but my guess is it will be an improvement since I'm putting more tread down to the ground, and the 11.5" vs the 11" should limit any bulging.

[nathangracey]

Fwiw, I'm running 20x11+34 rears w 305s
20x9+17 275s up front

Both rub when compressed.

[guarnibl]

Originally Posted by nathangracey

Fwiw, I'm running 20x11+34 rears w 305s
20x9+17 275s up front

Both rub when compressed.

Are you lowered?

[TahoeM3]

Not sure if it will fit, but I think that's a bit of overkill...no benefits to that size and you will have more side effects...tramlining, rubbing, etc.

[guarnibl]

Originally Posted by TahoeM3

Not sure if it will fit, but I think that's a bit of overkill...no benefits to that size and you will have more side effects...tramlining, rubbing, etc.

What do you mean no benefits? Obviously don't want to do it if it rubs. But I'd like to keep the front and rear as close to the same size as possible while increasing the amount of tire I can put to the pavement.

295/325 would be a 30mm tire difference vs the stock 20mm tire difference. Granted, ET's probably aren't at their limits either, so there's that too. Without adjusting sway bars, springs, or camber, this should technically result in an increase in under steer. However, the goal here is to get as much tire to the ground for increased grip. I can adjust other hardware to compensate appropriately. If I can't get 295/325 to fit, my next goal would be 295/305.

On my Boss 302, I was able to run a 295/325 (stock was 255 / 285), and utilize a different spring combination that created additional camber in the front. Combine that with R compound tires (Toyo R888) and a lowered ride height, the result was absolutely unreal. Ridiculous improvement over stock. The car became incredibly neutral, stuck to the road like glue, and turn-in was greatly improved. I never tracked it, but imagine it would have been even more pronounced there.

[TahoeM3]

Originally Posted by guarnibl

What do you mean no benefits? Obviously don't want to do it if it rubs. But I'd like to keep the front and rear as close to the same size as possible while increasing the amount of tire I can put to the pavement.

295/325 would be a 30mm tire difference vs the stock 20mm tire difference. Granted, ET's probably aren't at their limits either, so there's that too. Without adjusting sway bars, springs, or camber, this should technically result in an increase in under steer. However, the goal here is to get as much tire to the ground for increased grip. I can adjust other hardware to compensate appropriately. If I can't get 295/325 to fit, my next goal would be 295/305.

On my Boss 302, I was able to run a 295/325, and utilize a different spring combination that created additional camber in the front. Combine that with R compound tires and a lowered ride height, the result was absolutely unreal. Ridiculous improvement over stock. The car became incredibly neutral, stuck to the road like glue, and turn-in was greatly improved. I never tracked it, but imagine it would have been even more pronounced there.

Originally Posted by guarnibl

Not for track use, but I loved having wide front tires on my previously lowered RWD car. I'm planning on using the height adjustable KW springs so I can get between 15-35mm drop.

There's a law of diminishing returns, especially on a street-only car. Front-end grip is excellent with the stock front wheels/tires in my experience. Many have gone to 275 fronts, but beyond that the added weight of larger wheels and tires will likely impair handling while giving no added grip that you could possibly exploit on the street. And with up to a 35mm drop you will be rubbing badly. I believe the 275s on stock wheels only clear the wheel well by about 5 mm.

[guarnibl]

Originally Posted by TahoeM3

There's a law of diminishing returns, especially on a street-only car. Front-end grip is excellent with the stock front wheels/tires in my experience. Many have gone to 275 fronts, but beyond that the added weight of larger wheels and tires will likely impair handling while giving no added grip that you could possibly exploit on the street. And with up to a 35mm drop you will be rubbing badly. I believe the 275s on stock wheels only clear the wheel well by about 5 mm.

It's all about balance. I nailed it on the previous car. That's more or less what I'm going for here. No doubt the M is setup a lot more aggressive as well than the Boss was... as you probably figured. So there's probably less room for improvement with this car than my previous one. Even a slight increase in tire size on my 911 Turbo S was a pretty dramatic improvement. Trial and error I suppose... thankfully mostly everyone had already done the homework for me on the Mustang over the course of a couple years, since the car debuted in late 2010 and I didn't even get into the Boss until late 2012.

[TahoeM3]

Originally Posted by guarnibl

It's all about balance. I nailed it on the previous car. That's more or less what I'm going for here. No doubt the M is setup a lot more aggressive as well than the Boss was... as you probably figured. So there's probably less room for improvement with this car than my previous one. Even a slight increase in tire size on my 911 Turbo S was a pretty dramatic improvement.

The 2012 911 turbo S had 235 front tires. Going up 10-20 mm is one thing. Going up 40mm is another. As I say, diminishing returns.

[guarnibl]

Originally Posted by TahoeM3

The 2012 911 turbo S had 235 front tires. Going up 10-20 mm is one thing. Going up 40mm is another. As I say, diminishing returns.

Yep, probably right. I never went for a small increase on the prior Boss so I have no experience to say one way or another re: what it would have ended up like with a smaller front and smaller rear. Guess we'll see I know for sure I don't want to end up with rubbing though, or anything dragging out of my driveway... so I know I'll be limited. I want to stay as close to that 20mm difference front/rear as I can though.

[kitw]

Front: 275/30r19 fits with a 19x10et25 (it is VERY VERY close with the KW V3 but fit)

Rear: 295/30r19 or 305/30r19 will fit with a 19x11 et40

Those are the maximum "practical" sizes you can do (275/305) More than that gets a little silly. a 19x11.5 et45 might fit for the 315, but I haven't tried it.

[guarnibl]

Originally Posted by kitw

Front: 275/30r19 fits with a 19x10et25 (it is VERY VERY close with the KW V3 but fit)

Rear: 295/30r19 or 305/30r19 will fit with a 19x11 et40

Those are the maximum "practical" sizes you can do (275/305) More than that gets a little silly. a 19x11.5 et45 might fit for the 315, but I haven't tried it.

Good to know. Might have to go the 18 route then, or just run 275 front 295 rear.