Help decide wheel/tire sizing (RPF1 with Z1*)!
Nov 15, 2011, 08:09 AM
#1
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Help decide wheel/tire sizing (RPF1 with Z1*)!
I'm definitely getting Black Enkei RPF1's and Z1*s... can't decide on sizing though!
These are the current options I'm considering:
17x8 +35 with 235/45-17 | Weight = 15.5 + 27 = 42.5 | 2.3lbs savings vs stock | Super light, but high offset
17x8.5 +30 with 235/45-17 | Weight = 16 + 27 = 43 | 1.3lbs savings vs stock | Better offset at some weight cost
17x8.5 +30 with 255/40-17 | Weight = 16 + 28 = 44 | 0.8lbs savings vs stock | Better offset and wider tire at more weight cost
My stock setup was IX BBS's with 235 Z1* which was 17.8 + 27 = 44.8
I also ran X MR BBS's with 245/40-18 which weighed in at 19.5 + 27 = 46.5
I felt I could feel the difference between the X's and IX's which is 1.7lbs, so I'm trying to shoot for weight savings. That said, I also care about the "look" so a wider stance is a plus. Added grip of a wider tire would also be nice, though I tend to think 235's are more than sufficient for my setup (I'm lightly modded, likely putting ~320 to the wheels and this is likely not to change significantly).
The car is not a DD but is mostly street driven with light autox every season.
Input is much appreciated! Additional configs would also be considered!
Sources:
Enkei RPF1 Specs
Dunlop Z1*
These are the current options I'm considering:
17x8 +35 with 235/45-17 | Weight = 15.5 + 27 = 42.5 | 2.3lbs savings vs stock | Super light, but high offset
17x8.5 +30 with 235/45-17 | Weight = 16 + 27 = 43 | 1.3lbs savings vs stock | Better offset at some weight cost
17x8.5 +30 with 255/40-17 | Weight = 16 + 28 = 44 | 0.8lbs savings vs stock | Better offset and wider tire at more weight cost
My stock setup was IX BBS's with 235 Z1* which was 17.8 + 27 = 44.8
I also ran X MR BBS's with 245/40-18 which weighed in at 19.5 + 27 = 46.5
I felt I could feel the difference between the X's and IX's which is 1.7lbs, so I'm trying to shoot for weight savings. That said, I also care about the "look" so a wider stance is a plus. Added grip of a wider tire would also be nice, though I tend to think 235's are more than sufficient for my setup (I'm lightly modded, likely putting ~320 to the wheels and this is likely not to change significantly).
The car is not a DD but is mostly street driven with light autox every season.
Input is much appreciated! Additional configs would also be considered!
Sources:
Enkei RPF1 Specs
Dunlop Z1*
Nov 15, 2011, 10:04 AM
#3
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Yup I know those are the stock sizes, I've run both. Confused at your opinion? You think 17x8 +35 on 235s? Only thing I don't like about that combo is that its pretty sunk in from the fenders. The 18x8.5 +38 wheels sit .25" farther from the hub than stock IXs (6.35mm). The X's looked better than the stock IXs but still weren't quite perfect. The 17x8.5 +30s would be 14.35mm more than stock which would make them look more flush than the X's.
EDIT, calcs above were wrong.
EDIT, calcs above were wrong.
Last edited by Paulnsx; Nov 15, 2011 at 01:34 PM.
Nov 15, 2011, 11:23 AM
#7
Planning to stay with stock suspension? With your power and if you're autocrossing, I'd personally opt for 255 tires, although I personally think 8.5" is a bit narrower than optimal for that specific tire. It's not a high priority and I don't mean to sound shallow, but you mentioned looks several times, you should know that those sizes of RPF1 are butt ugly compared to the wider, lower offset ones. The face of the spokes/wheel are different.
I personally had the same wheels and tires, RPF1 in 17x9.5 with 245 Z1s autocrossing in STU with much less power than you and didn't feel they were heavy to any disadvantage. Multiple-time National STU champions ran the same thing, so I don't think it'll be any problem with you and your 320whp.
Best option- run them all, race, and tell us which was fastest and handled best
I personally had the same wheels and tires, RPF1 in 17x9.5 with 245 Z1s autocrossing in STU with much less power than you and didn't feel they were heavy to any disadvantage. Multiple-time National STU champions ran the same thing, so I don't think it'll be any problem with you and your 320whp.
Best option- run them all, race, and tell us which was fastest and handled best
Last edited by hokiruu; Nov 15, 2011 at 11:27 AM.
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Nov 15, 2011, 12:39 PM
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Thx for all the input! My suspension is currently stock shocks and Swift Sports. This might be changing in the relatively near future as my shocks are on the way out. I'll consider the 17x9 and 17x9.5 options
Nov 15, 2011, 12:44 PM
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any expected fitment issues with 17x9 +35 and 255/40-17s? These should put me 15.7mm wider than stock
UPDATE: looks like 17x9 +35 requires 20mm spacers up front. i think the 17x9.5+38 do too. i'd like to not run spacers.
UPDATE: looks like 17x9 +35 requires 20mm spacers up front. i think the 17x9.5+38 do too. i'd like to not run spacers.
Last edited by Paulnsx; Nov 15, 2011 at 12:52 PM.
Nov 15, 2011, 01:31 PM
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how about 17x8.5 +30 with 245/40-17?
- 245s should fit nicer on 8.5 wide wheels
- get a nicer stance (+14.35mm from stock)
- looks like it's the lightest package at only 42lbs
- rolling diameter is very close to stock at 1.44% under
- 245s should fit nicer on 8.5 wide wheels
- get a nicer stance (+14.35mm from stock)
- looks like it's the lightest package at only 42lbs
- rolling diameter is very close to stock at 1.44% under
Last edited by Paulnsx; Nov 15, 2011 at 01:35 PM.
Nov 16, 2011, 08:42 AM
#14
Paul, you are correct that the 9" and the 9.5" both require a 20mm spacer, but they look waaayyy better than the 8.5". I went from the 8.5"+30 to the 9.5"+38 and I love them.
I do get some rubbing on full lock, and I had to roll the rears as they would rub under compression when corning hard, but in the end it was all worth it.
I don't think you'll have any issues with the 8.5" and either a 245 or a 255 if thats what you decide to do.
I do get some rubbing on full lock, and I had to roll the rears as they would rub under compression when corning hard, but in the end it was all worth it.
I don't think you'll have any issues with the 8.5" and either a 245 or a 255 if thats what you decide to do.
Nov 16, 2011, 01:19 PM
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did you send another one? only got the one in response to the one i sent you earlier yesterday, thx for the help!
destroyed 1 of my ix bbs's (yay MA roads) EvoM thread. picked up a replacement but its' kind of beat up. keeping that set for possible race tires if i awnt to get that serious, might sell them down the road tho. mostly just to mix up the look and the rpf1's weigh less
got any pics of your current setup? thx for all the info!
Paul, you are correct that the 9" and the 9.5" both require a 20mm spacer, but they look waaayyy better than the 8.5". I went from the 8.5"+30 to the 9.5"+38 and I love them.
I do get some rubbing on full lock, and I had to roll the rears as they would rub under compression when corning hard, but in the end it was all worth it.
I don't think you'll have any issues with the 8.5" and either a 245 or a 255 if thats what you decide to do.
I do get some rubbing on full lock, and I had to roll the rears as they would rub under compression when corning hard, but in the end it was all worth it.
I don't think you'll have any issues with the 8.5" and either a 245 or a 255 if thats what you decide to do.
Last edited by Paulnsx; Nov 16, 2011 at 01:22 PM.