Any interest in Rota Slipstreams 16x8, 4x108?

[GAbOS]

Depends on the tire, but here's a thread on this very forum and 205 doesn't look that bad really.

http://www.fiestastforum.com/forum/threads/2161-BBS-RS-Replica?p=30797&viewfull=1#post30797

 

[eleven]

So, if these do indeed ship with an et of 45... If I run 15mm spacers, thats essentially a et30 wheel?

 

[RAAMaudio]

I agree on the offset, my 9" wheels are +35mm because that is what I can get though I run a 5mm spacer to clear the inside rim protector strip the Rival S comes with, why they put one on both sides of the tires is really odd. I am going to go down to a 2 or 3mm spacer when I find or make some up.

As for tires, the differences are enough in design and actual specs that often times a 205 is the faster tire on an 8" rim, not just in a rare case. I have been doing this for 48 years and also research a great deal on it, autocross, road race, HPDE, TT, and always confer with a few key sources that are full time into what works best. I even know of one team that runs 205 Hoosiers on 9" wheels(some of their tires are super wide like the 225/45/15 R6 I had on the 9's and could not fit them under the rear of the car even with the camber change and rolled and pulled as far as I could go, they were more like a 240 or wider)

The Miata guys that are in the know and provide the best selection of super low weight flow, roll, whatever formed wheels generally run 205 on 8, 225 on 9 and 245 on 10" wide wheels for a reason.

Some tires have a wider tread on the ground on wider wheels, the Rival S is one of those, measured them and wider than posted specs and proven faster by a many times national champion.

Overall there are too many variables to go by a simple standard, intended use of the tire, actual specs, known results already proven, WHP, torque curve.....

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Just to be clear, I think the super stretched setups are totally backwards, a silly trend, follow the leader, not clear thinking, etc.... the stretch that optimizes the performance is what I aim for, nothing more or less and many times no stretch is better. A bit of pinch, like in some autocross situations with limits to tire and wheel choices making a bit more rubber on the ground faster though giving up some feedback and control. That may be due to the fact the transitions are so quick the wheels do not have time to move around inside the tire as much as they would during the much longer average time on a road race course.

 

[MS67]

I get that a 205 may be faster on a 16x8 as opposed to a 16x7 since the sidewall is more stable and the contact patch is spread wider. But are you also saying that a 205/45/16 will be faster than a 225/45/16 on the same 16x8 wheel?

 

[polyol]

Typically it will not be faster all things being equal. On autox the wider the better. You go as far as practical...at least that is what I would recommend.

 

[gabe]

I think most of us get that, but in general a 205 is stretched on a 8" rim and a 225 is not. I get that every tire is different, but in general a 205 < 225 < 245. In general a 205 is just not a good fit on a 8" rim at all, maybe an odd one will but most will not.

Regardless, a stock offset with a wider rim is probably not a good idea. Moving to a 38 - 40mm offset is a good idea given the clearance.

The offset is 38mm. Wasn't spoken much of here on this thread but I'm pretty sure it was over email.

 

[RAAMaudio]

I agree, autocross wider is better, nearly if not always, then again if you have a dedicated autocross wheel and tire package, which I have done more than once, I put all the rubber on the ground that I can fit within the rules and the performance of each different tire.

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For other situations, which normally last longer than 3 less than 60 second sessions in a day, narrower on the right rim to give a bit of stretch will almost always be faster since the speeds are far higher and feeling what the car is doing becomes far more important.

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I am an on and off autocrosser since the early 70's and if had my choice every teen looking for a license would have to do at least a few autocrosses for part of the training, mine did. I met some of the greatest people I will ever know at events but eventually got to want to get more seat time so the track was what I got into and met many great people it was never as cool as being around the autocross crowd in WA, OR, CA, ID and NV places I have done so.

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Working out the best solution per each individuals needs is the best way to help them achieve their goals and when on the extreme end of the choices, there are almost always compromises.

That is why I have 6 track wheels and tires, 4 summer only wheels and tires and 4 high performance all season (really 3 season) wheels and tires for our car even though space and weight are a limit in the RV. If I wanted to also drive in the snow or rally the car I would need even more!

 

[GAbOS]

What Rick said.

You can only compare Auto-X settings to Auto-X. They use very extreme setups you would not use anywhere else.

If you are going to DD the car and not go full blown on an Auto-X setup that will eat your tires from DDing then go 205. Cheaper and the right tire will look perfect on the wheel and not disappoint.

Rick, Pretty sure I have a 3mm 4x100 57.1 (no ID lip) spacer laying around in CC.

 

[eleven]

So, if these do indeed ship with an et of 45... If I run 15mm spacers, thats essentially a et30 wheel?

 

[vegaspyder]

So, if these do indeed ship with an et of 45... If I run 15mm spacers, thats essentially a et30 wheel?

Yes, but he wrote above that they should be coming in a 38 offset.

 

[Ext569]

Past emails with 18racing confirm the offset should indeed be 38mm.

 

[RAAMaudio]

Thanks for the backup Gabos

Likely will finally be back in CC around 5-6 weeks from now, would be cool if you have the spacers

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If somebody ends up with +45 offset I would recommend 10mm spacers max.

 

[polyol]

^^^ I do like the information shared on here BTW. Everyone seems super helpful and not combative, opinionated is great...what it is all about.

Miata's do run some extreme stretch, usually because of the classes they are trying to compete in and overall fender/inside clearance. I have seen and personally ran some strange setups. Ive ran 245 and 275's on the exact same 8" rims (and same tire manufacturer/brand) and the 275 was clearly faster around a Autox course. So all things being equal, the wider the better if you can "fit it" for Autox. For road courses you are absolutely right, it would have been dumb to do this and certainly less predictable.

As for spacers, and im sure most people know this...on stock studs I would never run more than 3mm. Maybe 5mm with the right lugs for limited use. Any larger than that please please get longer studs. I have personally seen tires come off with 8mm spacers.

 

[RAAMaudio]

I have used longer studs in all my project cars for so many years it is a given to me and forget to mention it at times, not just longer but hopefully stronger as well, ARP used the most, thanks for bringing it up and I agree with your recommendations

I prefer to not use spacers at all but sometimes no choice but if I do so I do it right as we all should.

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I have ran 305's on a 10.5 wheel for autocross, Forester XT, took second place at a pro solo practice, 1.6 sixty foot time on a parking lot as well, it was about the widest/rim I have ran for that situation, my street Vette had 335's on 18x13's in the rear

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[polyol]

Yeah, ARP studs are really nice. Have them on my STi. Ideally you do not have to run spacers...that said I have stacks of them lol...

...also if you do run spacers, run hubcentric ones if possible. If they are permanent spacers for street use, then it is a must IMO.

 

[MS67]

Sent my deposit. I decided I'm going with 225/45/16 ZII Star Specs.

 

[ElijahSky]

Can I still get in on this deal!


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[MS67]

Shoot an e-mail over to sales@18racing.com and let them know you want to get in on the group buy. They'll send you an invoice for a deposit.

 

[ElijahSky]

Is 17lbs the correct weight? 15x7.5 +40 is 12 lbs. they are quoting me a different price as well. Higher of course.


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[MS67]

I've heard the 16x7s are around 13.5lbs and 16x8s are closer to 15lbs. But we'll have to find out whenever they come in. The price should be $675 shipped.