MicVelo

Well, your front tires are too tall. Stock is 225/45-18. In running a tire that is almost an inch taller than stock but running a stock 245/45 in the rear, your traction system (TCS or VDC) is activated because the delta between front and rear has exceeded what the computer wants to see; that is, the expected tolerance between F&R wheels speeds. It thinks that the rears are spinning because the wheel speed is more than 3% variance.

If you run stock sizes, you're fine.

Alternative to stock: 245/40 front and 275/40 rear.

spartikus1975

I like the 225/50/18 in the front it takes up the wheel gap , I just want to see if I can get away with a 255/45/18 in the rear. Also the fronts have a ton of tire life left the rears are needing to be replaced very soon.

MicVelo

Well, don't know why you're concerned with wheel gap with a worse potential safety issue like activating traction control when you're going hot. But your choice.

But ya, concern over wheel gap... If you're that concerned about the aesthetic, lower it.

Good news is that by running a slightly too tall tire in the rear with the too tall front *might* normalize the wheel speed differential to something tolerable to the ECM and cure the TCS triggering issue.

Leo Lee

quick question: I have a set of 370Z base 18" wheels on 2005 350Z without spacers. current front tire is 245/45/18 and is very close to front contral arm. Can it get a bit further away from control arm with smaller 225/45/18 tires?

MicVelo

You have two issues (only one germane to your question)

First, clearance problem is not due to tire width so much as it is with the wheel offset. ALL Z34 front wheels have much higher offset (+40mm +) compared to Z33 at ~30mm. This causes the wheel to be too close to suspension AND diminshes steering response.

The fix “could be” 225 section width tires but better solution are a set of 20mm spacers (bringing effective offset down to low 20s); a much better solution that gives double returns - clearance issue solved, steering response returned to normal, sharp and concise.

Other “problem” (not a biggie) is a 245/45 is a bit tall for the front. That’s usually a rear tire height. Front 18s should wear 245/40 (or 225/45).

Leo Lee

Thanks Mic. Very valuable suggestions

DennyB

I'm a new member here and I have a question that kind of fits in with this thread. My 2004 350z Roadster had 20" aftermarket wheels on it when I bought it a few months ago. I recently bought a set of 2010 370z wheels that I thought would be fairly simple to bolt on. When they wouldn't fit I found out that the center holes of the 370z wheels are 66 mm but the "hubs" on my car are 73 mm. I've been reading threads here and thought I read that all 350z's had 66 mm hubs. Is that right or wrong?

MicVelo

66.1mm hubs to be precise.

I'm betting that you have some 73.1mm hub rings stuck to the hub, particularly if they're aluminum. The hub rings are used to fit the aftermarket wheels - which are largely 73.1 center bore - to many different cars using appropriately sized hub rings. (In this case, "73.1 to 66.1" rings"). I'm guessing you either read the marking on the hub or mic'd them. Well, no hubs have the size marked on them so if yours do, they're hub rings. If you mic'd them, they're still hub rings. Laff. Pry them off and you're good to go.

Do not forget two things when fitting Z34 wheels to a Z33: KEY - use only the appropriate 12x1.25 *SHANKED* OE type 370Z lug nuts. Stock Z33 or aftermarket conical lugs (AKA "tuner lugs" with the conical seat) DO NOT WORK and will loosen. Secondly, front 370Z wheels are high offset varying from 40 to 47mm depending on style. You need spacers to properly fit them. Tell us which wheels you have (and size tires you are fitting them with) and a recommendation can be made. Generally speaking, you'll need at least 20mm spacers.

DennyB

Thanks for the reply MicVelo! Yes, I mic'd them with a really cheap mic. I'll take a closer look at them today. Hopefully you are right about the hub rings. I was afraid that the previous owner had swapped brake rotors (if that's even possible) to accommodate the wheels. I have the numbers from the backside of the 370z wheels but I'm not sure which of them would help identify them other than the offsets. The front wheels are 18x8 with 43 mm offset and the rear are 18x9 with 15 mm offset. The wheels have decent tires on them now but they are a little undersized, 225/40/ZR 18. I'll probably buy some new tires in the original sizes.

DennyB

MicVelo, you were absolutely right about the rings. The one I checked even had a decal that said 73 mm. I just tried one of the rear wheels without the ring and of course it fits just fine now. Thanks for clearing that up for me.

The lug bolts or studs seem a little short but it's hard to tell because of the way they are recessed. From reading some of the threads I understand that I might need longer studs with some spacers, but should the original studs be long enough if no spacer is being used? I understand what you told me about the lug nuts. I'll be looking for some today.

Mully

The 370Z lugs are a shank style (versus acorn for the 350Z), meaning they actually extend into the holes where the wheel studs protrude. These will allow you to grab a sufficient amount of thread.

As for spacers, if you get slip-ons you will need extended studs. If you get bolt-ons, you can use your stock ones. If you are going with 20mm, you should get bolt-ons.

DennyB

Thanks Mully! Just to be sure, is this the correct style lug nut that I need? I found this picture in another thread.

Mully

No problem. Yes that is the style lug you'll need.

DennyB

Thanks again! I'll start reading some old threads to try to learn a little bit about spacers for the front now.

MicVelo

Based on your description (and that they are 18s), guessing you have these (Z34 base wheels)...


With a +43, 8" wheel, I'd recommend 20 or even 25mm spacers for the front wheels. (Rears won't need spacers with +15mm offset.) And yes, bolt on type spacers.

The lugs you and Mully talked about are exactly what's needed to get into the wheel nut recess and into the lug hole to grab the stud securely.

DennyB

McVelo, yes those are the wheels I have. I really like those and the ones I have are in great condition. I appreciate the help very much. I was almost ready to put those wheels back on Craiglist and look for some original 2004 wheels. Now I know that they wouldn't have worked either until I removed those hub rings. ;<)

I've been reading the spacer threads and I know what to look for but I do want some that are fairly good quality. I'm almost 64 years old and don't plan on doing any racing, but I do like to push it a little on curvy roads. I drove the Z on The Dragon near the Tennessee-North Carolina state line last summer. It would have been a lot more fun if those slow motorcycles would have gotten out of the way.

Mully

For what it's worth, I run BORA spacers on the rear of my desert truck. Mine are 2" thick, billet, and hub / wheel centric. I've ran them for 4 years and thousands of hard desert miles without issue. I highly recommend them. Their street car brand is Adaptec, which I'm assuming will be of the same quality as the BORA.

https://www.motorsport-tech.com/bora.html

MicVelo

Happy to help. I've BTDT with the hub rings. I now use the plastic ones (instead of the aluminum rings). They still stick but not as tightly as the aluminum. Good to not have to use any hubrings with your OE wheels. As far as age, almost there with ya and still playing like I was 20.

Concur. I have (or had since I usually give the spacers away when I sell a set of wheels if the buyer needs them) a couple of sets of Adaptec spacers amongst the plethora of spacers in my "wheel stuff" drawer. They're good quality.

To be honest, I have some name brand ones and a few sets of inexpensive ones from Premier Auto Accessories out of Fremont, CA (found on EBay). I've run 'em all with no issues whatsoever. But I do make it a point to check torque on both the spacers AND the wheel lugs from time to time. Just cheap insurance. I used to swap wheels every couple of months but now, not so much. (Hence, re-install spacers that go with each different wheel set) Took wheels off car recently after a year and a half (longest interval ever) and just for kicks, checked torque on them before removing; still spot on. (But in all fairness and full disclosure, I drive the Z less than a 1,000 miles a year.)

DennyB

Thanks Mully and Mic Velo! I'll Take a look at the Adaptec spacers.

DennyB

Sorry guys but I have another question. I'm going to buy some news tires but I'm confused at what is original for the 2010 370z wheels that I've got. Most of the info that I've seen says that the OEM front tire size is 225/50/18 and the rear is 245/45/18. Those sizes seem to match pretty well using an online tire size calculator that I tried, but I've seen some conflicting information in some of the threads. Are those the correct sizes?