z461

So..according to LUke@tirerack. The real offsets for the GTC should be +39mm out front and +37mm out rear, rather than the +27mm and +24mm that people have been buying (like skidazzle). Hmm..wonder how that would look.

jran76

iTrader: (1)

I am confused, by the more I read. I agree with what Luke is saying, but why does Nismo list such low offsets. I really want to order some Volk's (LE, TE, GT-C, or GramLights), but I am lost. I am at the point now, that I would say anything from 22-40 would work, but that seems like a lot a variance. The look of the wheels on the Redline Brembo looks good, but they are an 11 inch wheel, anything lower (9.5) seems like it would be tucked in too much.

OK, enough rambling, but I am confused.... Someone help me out.

sdpearso

OK, so I amno expert but here's what I take from all of this.

Luke recommends xyz offsets based on his fitment testing and knowledge of how these changes affect performance/handling.

I agree when Luke says that the offsets listed by Volk will change the scrub radius and Ackerman Angles and ... I agree that these changes will affect handling. I believe that Luke knows what he's talking about.

But, that does not mean that these changes will be negative.

The 350z is a sports car and was built to be a sports car. But it was built to be a sports car that is driven on the street, and maybe occasionaly the track, by ordinary people. Changing the scrub radius will change the handling but maybe for the better. Moving the wheels out slightly will help improve the understeer that this car has. But where is the line where things start getting worse. Maybe +27 offset is good and +22 is too much. Maybe +22 is optimal.

jran76

iTrader: (1)

So, you seem as confused as I do ....

Just joking, I agree, but you pose a lot of questions that have not been answered, so it is speculation that the changes will be positive (although they very well could be). I think a lower offset with the wheels pushed out further would improve handling (wider track), and reduce understeer (I agree with you). I also think NISMO has the best idea as to what would be best, from a performance perspective.....

sdpearso

That's exactly what I am saying. I don't know what is best and what is crossing the line. But I think NISMO knows what's up if anyone does at this point.

Luke@tirerack

350z, 300zx, g35, C32, M3 ... the vehicle in question doesn't matter .... vehicle dynamics is vehicle dynamics ... by altering scrub radius, ackerman angle and roll center the vehicle will not handle as well. Some of the changes in dynamics may possibly be overcome by using wider tires but not all of them .... tramlining, tracking, bearing wear, tire wear, etc will all occur by using the offsets that belong on a Skyline GT-R.

Pontiac is not 100% right ... wider is not always better unless it is designed wider from the beginning....

jran76

iTrader: (1)

I don't necesarily disagree with you, and you are obviously much more knowledgable on this subject than I. But, why is NISMO recomending such a low offset, along with Mackin (the US distributor for Volk)? One thing though, NISMO's recomendations are for the S-tune suspension package, which seems to be wider than stock, which could be a reason for the lower offset, but I do not believe they would comprimise any performance for that reason. I have read through all the post, and I understand what you are saying, but I need proof, as it relates to the Z, not just general speculation (that is probably true, but like sdpearso said where is the line that you start to loose some performace).

SKiDaZZLe

here is my viewpoint:

i got 27/24 for looks on the street. plain and simple. i dont street race, nor do I plan on auto-x'ing on these rims...

my stock wheels will be fitted with R compound tires for the racing season. this should get my scrub crap and angle crap alright for handling.

YMMV, but my car still looks really good

m

SKiDaZZLe

if an 11" rim is using +40 offset, then a 9.5" rim would need half of the width difference subtracted from the offset to get the same look of the wheel not looking pushed in.

this would equate to: 40mm - (1/2)*((11"-9.5")*25.4) = 40mm - 19mm" , which equals 21mm...

you see, a 21/22mm rim on a 9.5" width will push out the wheel to look just like that red brembo car.

is any of this math wrong, Luke? i understand it might degrade performance, but the look will be the same, right?

m

sdpearso

This I disagree with Luke. The car does matter. If the manufacturer built a car with conservative offsets because they wanted more conservative handling (or because they wanted to be able to sell upgrades) the optimal offset could be different. This is why different cars are built with different offsets. Your theory is correct in that any change in offset will affect all those characteristics. But if the car is built with a conservative offset, a more aggressive offset could help. But to say that pushing the wheels out is bad on all cars or pushing them in on all cars is wrong. Vehicle dynamics are vehicle dynamics but all cars have different dynamics to start with.

This is true if the "theoretical line" is crossed. But where is that line? Who's to say that the 350z wasn't built to handle a bit less offset.

We are not talking about offsets that belong on a Skyline GT-R. The wheels in question in this thread are the GT-C and NISMO wheels. Both have offsets that are closer to stock than the alleged GT-R spec wheels.

True, wider is not always better unless it is designed wider from the beginning. What I read from NISMO is that the 350z was designed to benefit from a little wider offset.

Luke, you may have some experience/testing with the 350z that answers all of this but other than general handling experience and fitment with the 350z, I haven't seen you post anything that says you or your company has tested different offsets and the results were XYZ. This may be because you don't want to give away your research but that's just the pickle we're in.

rodH

iTrader: (2)

sorry if this is too far off topic, it there a website that explains and converts different offsets???

ANd how would I figure out how to get a certain "look"? SKIDAZZLE and that car that Luke posted look good.

Driven

rodH,

Believe it or not, I believe it is as simple as this: If you want an 8" wheel to sit in the exact depth from the fender lip as you saw in the red Brembo picture you need a 11mm+ offset. If you want a 9" wheel to sit the same you need a 22mm+ offset, and for a 10" you need a 33mm+ offset. Each of these equates to a 44mm+ offset on an 11" wheel. Just remember you are saying you like that depth on a LOWERED CAR!!! If you are running stock, that gap is going to be larger. Additionally, this does not address all the issues brought up by Luke....it is only an anwser to your question. Technically the Brembo car is off of stock parameters also and should have an offset of 55mm+ on the 11" to equate to the 33mm+ on the 8" (Performance...don't know the stock for the 8.5" Track) So it is "tucked" 11mm in order to clear the fender completely when lowered. (I think all that is correct...Luke please correct me cause all of this is from our conversation this afternoon...I could have it wrong)

roberto350z

Maybe dont go to +25, but +39? Yuck! I still like +33 +30 .

but wait....what size are we talking for the above?

rodH

iTrader: (2)

Driven.

so what would be the conversions for Skidazzles LOOK in different widths/off sets??

THANX for your help

veilside z

Shaun, I agree!
------------------------------
quote:

Originally posted by LS350Z
Until I see graphs, charts, data I'm calling BS. I haven't taken the time to get the information myself since I just got my Z so I don't have the answer yet either. Likewise, I don't think you have the data. If you do provide it otherwise remove your statement. I know suspension theory, design, dynamics, and everything else and I know when someone doesn't have the data to support their claims.
--------------------------------
Wider = Better or Worse? Until people can substantiate their statements with accurate data I will go with the "experts" at Nissan Motorsport & Rays on the offset matter.

Luke@tirerack

yeah, it's really hard to believe people, who are in a different country, would tell you something to sell products they have on the shelves rather than tell you the truth only to be forced to build a product specifically for your application. Your so-called experts are leading you down a long and incorrect road ... I would be happy to prove all of what I have said at any of the 5-6 tracks I frequent in the summer by posting better lap times in a correct setup car as opposed the the incorrectly annoited selections and specifications you are being fed. We have spent countless hours doing the research for this car and have a history of being the most accurate and informed experts in our industry. Why would companies like Brembo come to us when they need help if that wasn't the case.

I'm not going to argue the point with you guys adnausieum I have supplied the facts .... sorry if they don't agree with what you have been told....

think about this ... all of the wheels that have been mentioned are Volks, Rays, Axxis and a few others ...we do not offer any of these wheels so, I have no reason to lead you astray. I have no vested interest and nothing to gain in this discussion .... unlike others .... Even the Rays Engineering guys at SEMA admitted that their recommendations are based on what they currently produce not on what the car requires.

Driven

Make it easy on me (so I don't need to search...I'm lazy) what were Skiddazzle's respective offsets and wheel widths? I remember him saying 24/27 was this front to rear? And widths?

SKiDaZZLe

27 front 8.5"
24 rear 9.5"

Sanderman

Welcome to the site Luke. It's a bit pathetic to watch wishful thinking neophytes yank things out of their *** in the face of someone who brings data and experience to the table.

Maybe you could answer one thing for me instead. What is the widest rubber you can put on the stock track 8 and 8.5 inch rims? I'm not concerned about looks or bulging sidewalls here - just how much rubber I can get on the road witout putting wider heavier wheels on the car.

Thanks,

joe

sdpearso

Oh great Joe. So you take a site with "wishfull thinking neophytes who yank things out of their ***" and you add name calling. I'm glad you're here.

I personally respect Luke's experience and opinion, but it is an opinion, even if it is based on experience. I also respect NISMO's opinion and experience. That is why Luke's opinion is questioned so frequently.

Debates are a good way of weeding out facts. Without a little debate this site would be just another advertising page.

I know that Luke is new to this site within the last week and is posting info that goes against what we have been hearing for months now from well respected tuners, including Nissan Motorsports (NISMO). I think it's only healthy and natural for Luke to have to prove himself and his facts.