nbdyfcnsqnc

>> Mini rant - I really wish I could edit something older than 10 minutes on this forum.

I don't know why it's like that either. But if you ever need to make a correction like that, you can PM me or one of the other mods, and we can do it.

RedBird

Oh, well I thought this was my thread but I guess not.

kosmic

Gotta share with the other kids, too.

Seriously though, threads often take on a life of their own. There has been a lot of good info in this thread and I'm working on getting more from Fritz...

Just think, after this thread is all done, you should have enough information to make the perfect wheel/tire choice for your car.

apharmdb

iTrader: (1)

For you guys running the same sized tires all around, do you have any problems with TCS or VDC? I would like to do something like this for the track but don't want to run into any issues. Thinking of doing 17's all around though, perhaps 255/40/17, that is if I can find folks who have done it and have on track impressions.

SilverstoneZ

great thread exactly what I was looking for since I am in the market for 18" wheels and looking into tire size.

nbdyfcnsqnc

>> For you guys running the same sized tires all around, do you have any problems with TCS or VDC?

I think VDC would have a problem based on the explanation in the link posted above, because it will get a false positive on wheel slippage.

FritzMan

First of all, running the same tires front and rear will not effect VDC/TSC. I've been driving that setup for the past 16 months (summer & winter tires) with zero issues.

The rear can accomodate a larger range of offsets and widths than the front, so it's important to determine the front width and size first and then match the rear and make it look good with a small spacer. I've always wondered how a Nismo 18x9.5" 30mm would look on the front. The SCC article claims it fits and insinuates everything looks nice until the offset creeps up to 25mm (wheel is pushed out another 5mm). It doesn't sound like much, but you'd be surprised how much a 25mm spacer pushes a stock wheel out.

Personally, I always prefer a more conservative style (bigger bite than bark) so I like to round down instead of pushing the envelope. As mentioned in an earlier post, my ideal setup would be to run a 18x9 front/rear with a 30mm offset and a 10-15mm rear spacer (depending on tire). My logic is to keep the front offset close to the same as OEM allowing the increased 1" width over stock to be evenly distributed on either side of the scrub radius line resulting in OEM-like steering behaviour. You could try and squeeze a 9.5" rim with the same offsets (like SCC did) but I don't think the potential rubbing/asthetics risks offset performance gain (if any). BTW, 25mm could work, but you'll have to be more conservative with tire widths if you go that route.

I can't comment on the brake clearance because different brake kits and rim styles all have different clearance - at times regardless of offset. Two different 30mm offset 18x9 rims could have different brake clearance simply due to the spoke/mesh design as it leaves the hub and connects to the rim. Best to call the brake manufactuer prior to ordering the rims. Usually the rims with "fat lips" have issues.

Tire selection depends a lot on budget, and performance. Unfortunately they don't all make the same widths so you'll have to keep that in mind. Personally I'd look for a 255/40 or 265/40 setup. 275/40 is a popular size that will fit on a 9" rim but I personally find the sidewall a little too thick for my tastes (yes, asthetics do come into play occasionally).

I'm very interested in seeing how the new Falken Azenis RT-615 performs. They've apparently improved their wet weather performance and the dry stick is as good as the brands mentioned above (at a cheaper price I might add). Best of all, they make a really cool size of 255/40/18 which would work perfect on 18x9 rims. It may not be the fattest tire but I can assure you you'll have *plenty* of grip to play with the big boys. ;-)

BTW, when you play with rear tire sizing (height) you will effect the speedo. Nothing dramatic, only about -3mph with the sizes mentions above.

knight_white99

iTrader: (5)

apharmdb,

Go back and read my post earlier in this thread. Same size all around works great on the track; and, like FritzMan, I have not had any VDC issues so far. I'm running 18x9's with a 35mm offset (no spacers) and 265/35's, which give a HUGE footprint. I think that size tire is about as big as I am comfortable running at the front (no rubbing issues, but the clearance is minimal - I would think 275/35 or 275/40 wpould rub).

Also as Fritzman says, just a minor difference in speedo calibration.

phile

nm, :P

mena661

What wheels are you running and do you have pics? Thanks.

knight_white99

iTrader: (5)

I am running ADR Kasai wheels as my track wheels (these are split 5 spoke). You can find these on the web with a search quite easily. Bought them 'cause they were cheap ($530 shipped for all 4). They are also a few pounds lighter than the stock 18x8" wheels. If I had more money, there are nicer wheels out there in the same size. I also chose these since they fit with plenty of room over my Stop Tech brakes. Sorry, don't have any pics of that setup at the moment. I guess I will have to take pics of the several sets of wheels that I have so you guys can have a look.

mena661

Thanks for the reply. I was looking at getting some Gram Lights 57S but the closest size is 18x9.5. Not sure if that will be a problem with the 265/35's you mentioned. Would it be alright with a +30 offset?

knight_white99

iTrader: (5)

265/35's with an 18x9.5 wheel is fine. Offset of 30mm sounds pretty good too, as that is the exact same size as the rear Nismo wheel that Sports Compact Car Magazine (SCC) tried fitting to the front of their Project Z car. However, I can't swear to you that will work because I have not tried it myself. They had some minor rubbing issues with a 275/40 tire. On the rear, that setup would be fine. On the front, I think a 9.5" wheel is about as big as you can fit, and the offset (and tire size) would need to be perfect, otherwise you will rub either on the inside against the upright or on the outside against the fender. With my current setup, I am not rubbing anywhere. Of course, there is less chance of rubbing with a 265/35 tire than a 275/40 size tire.

Keep in mind that if your car is lowered, or you have a good deal of negative camber, there could be aggravated rubbing issues on the inside of the wheel/tire with the upright with a 9.5" wide wheel. The SCC Project Z was NOT lowered, if I recall.

Also note that with my 265/35 tires, the gearing is slightly changed. On the track, this is fine. On the street, there will be some minor speedometer error (a few %). You will run a higher rpm for a given true speed that on your stock setup. You may want to use a 255/40 or 265/40 for the street. I am using the 265/35 tire size since I got them cheap as well, and I am running at high rpm for the track anyway.

One thing is for sure, the car will certainly understeer less with the same setup front and rear. You may even get some oversteer (such as they experienced at SCC), but I think that can mostly be adjusted with sway bar settings. Personally, I think the car is much better handling this way, but your feeling may be different.

mena661

The SCC mag car now has the Nismo suspension, although I don't remember if they mentioned any rubbing issues. I need to find that article. Sounds like a 265/40 would be a good choice. And the reason I want the same tire at all four's is because of the SCC article. I like that they were able to pull 1.0g on street tires and, more importantly, eliminated the understeer. Understeer is probably safer for a track noob like me but it's no fun plowing the front tires at ~.83g on an off ramp or mountain road when you know the car could feel a lot better and grip more with less understeer. I have quite a bit of self control and would not over do it on public roads. Thanks much for the info.