215 tires + 300hp?

[stanhayward]

Hey I didn't think this fit in any of the other discussions but I'm wondering about the correct tire sizes for a 300hp+ 325i. Right now my car only has about 200-205 hp from exhaust, intake, MAF & chip and is rolling on 205/50/16 Yokohama S Drives and all is well. My problem is is that I'm looking to make around 300hp from either an engine swap or FI. I have a 9 inch rear wheel so I could get a set of 215 S Drives, but will this be enough? Any help would be greatly appreciated, I don't have experience with high hp E30s... yet!

[travish325]

First off your car does not have 205hp.

Second why have a 9 inch rim and a 215 tire? Stretched tires stance and high hp do not go together. With a 215 depending on your tire set up you will have some traction issues on launches and hard gear changes (which is going to be a problem on any higher hp e30)

Id try to squeeze a bigger tire under it imho.

[unevolved]

First off your car does not have 205hp.

[FredK]

You might want to use a stickier compound of tire. If you're driving this car on the street, then really it won't matter if you have a 205 or a 215mm wide tire.

Getting 300 whp won't automatically make your car a widowmaker, but you'll have to dial back your right foot.

[stanhayward]

Okay thanks. My bad on the horsepower, I thought a complete exhaust system with headers would make about 180 and then another 20 for the MAF and chip with intake. How far am I off by?

[travish325]

okay thanks. My bad on the horsepower, i thought a complete exhaust system with headers would make about 180 and then another 20 for the maf and chip with intake. How far am i off by?

25

[stanhayward]

Second why have a 9 inch rim and a 215 tire? Stretched tires stance and high hp do not go together.

About this, I know that stretch and stance aren't the best for performance but I like the look and I'm not building a race car so I'm not worried about this. I like the occasional hard launch, though, so I don't want to spin tires through 3 gears is all. Thanks for the heads up, though!

[stanhayward]

25

That much? The engine just had everything replaced so should make about stock horsepower and then even just the MAF and chip are dyno proven by Miller Performance to add 16whp. Then I have the KAmotors carbon intake and Ireland Engineering Exhaust components. I find it hard to believe that all of that only added 12 horsepower at the crank.

[travish325]

Its your car so do what you want.

I liked that look to but I tried running 500hp on a 225 tire stretched on 9.5in rims and all I did was eat tires and not go fast lol Im a little more on the performance side now so Im liking the fat tires and actually moving and not smoking my tires off.

[unevolved]

That much? The engine just had everything replaced so should make about stock horsepower and then even just the MAF and chip are dyno proven by Miller Performance to add 16whp. Then I have the KAmotors carbon intake and Ireland Engineering Exhaust components. I find it hard to believe that all of that only added 12 horsepower at the crank.

Stock at the flywheel, maybe, then factor in 15-18% drivetrain losses and marketing fudging. If you don't believe him, throw it on a dyno and find out what you're ACTUALLY making.

[ak-]

The tire choice is fine.
Differential plays a good influential roll too.

[stanhayward]

I also forgot to mention that I would install a 2.93 diff. Would this help? Obviously not for a launch, but for a 3rd gear pull?

[stanhayward]

Stock at the flywheel, maybe, then factor in 15-18% drivetrain losses and marketing fudging. If you don't believe him, throw it on a dyno and find out what you're ACTUALLY making.

I was talking 200 at the flywheel

[travish325]

I also forgot to mention that I would install a 2.93 diff. Would this help? Obviously not for a launch, but for a 3rd gear pull?

would help huge with a turbo set up

[fronton]

I also forgot to mention that I would install a 2.93 diff. Would this help? Obviously not for a launch, but for a 3rd gear pull?

2.93 will help you keep traction because it decreases your acceleration ratio equally in all gears. 3rd gear pull is the same 20% slower than first gear would be vs 3.73. 215 is enough tire for 300hp at with 2.93 diff as long as they aren't all seasons. I would not drop to 2.93 though unless you are 95% highway miles and only care about MPG