New Wheel and Tire Setup

LastNightsPants

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Hey everyone. I recently scratch up my OEM rims real good and the 4S's are about to ware out, so that gives me a good excuse to get some new, wider and little bit lighter wheels. Right now at my price range and based on my tastes I'm thinking of grabbing either MRR m350s or Apex SM-10s.

From what I can tell on a PP1 the widest front wheel and tire you can do without any mods is a 19/10 inch wheel with 285/35 tires on them. But my question is for the back. Should I run a square setup or should i go 19/11 inch with 305/30?

Its mostly a daily driver but my plan is to start doing autocross and maybe some track days (road) later this summer or early next year. My though is to get the 305's since I was told by a few other that for a novice driver its understeer is easier to control then oversteer. Plus as a bonus I like fat tires.

Also speaking of tires, what tires would you all recommend. I'm leaning on RE-71Rs.

I'm planing on keeping the OEM rims and sticking some cheaper maybe all seasons on it. The plan for the new wheels is to use them as nice weather/light drizzle cruising tires as well as autocross and the track. And when ever the weather isn't looking so good for a while switch to the OEM wheels

My concern with the tires is if I get lazy or forget to check the weather and get caught out in a heavier rain, can I still safely drive the car with these tires if I drive carefully?

What do you guys think?
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NightmareMoon

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If you want to track and autox, better stick to a squared 10" setup. Ideally you'd have a square 11" setup for those purposes, but initial costs are a bit higher (need to get extended from studs and slip on 25mm spacers, and likely even camber plates and a good alignment), and also consumable costs are higher (305 wide tires are usually more expensive than 285s). 285s on 10" wheels is a great starting point and won't be holdning a new driver back. The downsides with 10/11 staggered are two fold - they'll mess up the handling balance (the wider 11" rear is worse for handling than just being 10" square), and you won't be able to rotate tires. Believe me, when you're tracking or autocrossing, you need to squeeze every last lap out of the tires, and you won't like throwing out rear tires early because your fronts are dead.

Personally I went with the SM-10s, 'cause they're awesome. The M350s will get the job done too.

For tires, RE71R are ok in the rainstorms down to about 1/2 tread. After that they will hydroplane more easily than many other street tires. Standing water is the problem, not wet roads. If you slow down you should be ok if you do get caught. Above 50mph cars hydroplaning starts to get a lot worse. They are really great tires for grip, but also forgiving breakaway. They won't last super long if you're doing triple duty on them. Expect maybe 90-120 autox runs if thats all you're doing (and if you have good camber). If you ONLY drove them on the street, you'd probably get 10k miles out of them. If you're doing all three, then well, they won't make it to 10k OR 100 autox runs.
 
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LastNightsPants

LastNightsPants

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they'll mess up the handling balance (the wider 11" rear is worse for handling than just being 10" square)
I've heard this alot but I don't really understand why that is.

Also the 10s for those wheels only have a +40 offset, I think the stock pp1 has a +52 offset, is that gonna be an issue?
 

CORNYOTE

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I'm going 285/35 on a 19x10 and a 325/30 on a 19x11 with Toyo R888R's
 

CORNYOTE

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Biggest, fattest and stickiest thing I could fit. 800+whp whipple issues.
 

NightmareMoon

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I've heard this alot but I don't really understand why that is.

Also the 10s for those wheels only have a +40 offset, I think the stock pp1 has a +52 offset, is that gonna be an issue?
yeah I know its counter-intuitive, but to get a car around a corner, you need all four tires to reach the limit about the same time, or else its just an understeering mess. Before you can power out of a corner, you need to get the car rotated. For the 2/3 of the cornering phases, you can't really turn any faster than the front tires will allow, and the ability to corner in the second phase (mid corner) is very sensitive to balance. Powering out of the corner, sure you'd like those wide tires, but that's only 1/3 of the time spent in the corner.
 

CORNYOTE

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yeah I know its counter-intuitive, but to get a car around a corner, you need all four tires to reach the limit about the same time, or else its just an understeering mess. Before you can power out of a corner, you need to get the car rotated. For the 2/3 of the cornering phases, you can't really turn any faster than the front tires will allow, and the ability to corner in the second phase (mid corner) is very sensitive to balance. Powering out of the corner, sure you'd like those wide tires, but that's only 1/3 of the time spent in the corner.
I can understand that theory, but disagree completely. If you look at any road course purpose car, they’re almost always staggered. I mean look at F1. Going into a turn you should be continuing to brake hard halfway into the apex. The weight transfer will put the majority of the traction responsibility on that front outermost tire and with weight transfer it will have more traction than the rest. Coming out of a turn you should be increasing throttle, which in turn again changes the weight bias.

Your theory maintains that the car always maintains a center bias, which is almost never true at any point during a course.
 

BmacIL

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I can understand that theory, but disagree completely. If you look at any road course purpose car, they’re almost always staggered. I mean look at F1. Going into a turn you should be continuing to brake hard halfway into the apex. The weight transfer will put the majority of the traction responsibility on that front outermost tire and with weight transfer it will have more traction than the rest. Coming out of a turn you should be increasing throttle, which in turn again changes the weight bias.

Your theory maintains that the car always maintains a center bias, which is almost never true at any point during a course.
Yeah, uh, go try it wise guy. Heavy, and front heavy car.
 

CORNYOTE

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Yeah, uh, go try it wise guy. Heavy, and front heavy car.
Not trying to he a wise guy at all. I’ve never noticed a difference but i haven’t ran two different setups on the same car either.

Just saying tons of fast cars on the track and almost every one i’ve seen is staggered.
 

NightmareMoon

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Not trying to he a wise guy at all. I’ve never noticed a difference but i haven’t ran two different setups on the same car either.

Just saying tons of fast cars on the track and almost every one i’ve seen is staggered.
... yup lots of staggered cars and tons of them are square too. I’m only talking about S550 Mustangs. Other cars have different suspension designs, weight ratios, and fender clearances.

I’m sorry I cant better explain why square works better than staggered,. Ask anybody here who has spent significant time on a track or autox, you’ll get the same answer.

I’ve personally burnt through 5 and 1/2 sets of tires on track or autocrossing in my ‘16 Gt, and do occasionally win events in my class.

I will say that your idea of always braking down to the apex isn’t actually correct for all corners. I used to drive most corners that way, and my last couple of track instructors have broken me of the habit. For many corners, you only trail brake long enough to get the car pointed towards the apex and then you actually roll for a bit down to the apex where you pick up throttle. If you’re always braking down to the apex you are probably over-slowing, I was.

Then there are other handling situations like esses and slaloms as well.
 

bnightstar

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Not trying to he a wise guy at all. I’ve never noticed a difference but i haven’t ran two different setups on the same car either.

Just saying tons of fast cars on the track and almost every one i’ve seen is staggered.
Ford Racing School is running 285/35 square on there school cars. I suppose it's not because they can't afford to run Staggered. I still wonder what wheels they are using since the cars have what looks like a PP wheels on them.
 
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