Datsun Roadster Forum-311s.org

If i'm going to make the transition to stock class, I'm going to need some wheels with the same diameter, width, and an offset within a quarter inch of the original.

The diameter is 14. The width is 4.5. What is the original offset?

Thanks in advance
Steve

I know they are not zero offset. I have some stock steel rims in the shed. I will take some measurements and figure out what the offset/backspace is. It probably will not get done until next week as I will be busy driving the -hit out of a roadster all weekend. Maybe someone else will come through sooner.

Steve

Thanks Steve. I would appreciate it. Of course, be sure to check and see if someone comes through before you go to the trouble.

Have fun this weekend.

Thanks again,
S.

What a great weekend at the track! I had a ball. The stock rims I have are actually 5-3/4" wide. The backspace is 3-1/2". Divide 5-3/4" by 2 to get the wheel centerline which equals 2.875". Subtract the backspace 3-1/2" from 2.875" and you get an offset of -.625" or negative 15.875 MM. Minilites are I believe -16 MM amd they fit perfectly. Now I know why. If you go with a wider wheels you must use both backset an offset to get a good fit. Hope this helps.

Steve

Steve,

Thanks for the measurement. Good to hear you had fun at the track. Which track?

Now, not that I'm unappreciative, but are you sure the 5.625 would be Stock width for the Roadster? I did a search on the Datsun List and came up with two posts where they say 4.5" is stock. And I remember a comment from someone's web site (Steve Nelson?) where he said he autocrossed a roadster in sotck class and complained about having to find 4.5" alloys. They did mention stock wheels from 240Zs being 5.5" wide.

I'd love to fit 5.5" wide wheels on there, but was hoping to someday get into regionals or nationals where I'd like to be confident that I've my car classed where it's supposed to be.

Again, Steve, thanks a lot for your help. I really appreciate it.

S.

It could be the way I measured the rims. I went from outside to outside when maybe I should have measured from inside to inside where the tire fits. I will measure again when I get home. I do know they came off of one of my roadsters and have the tabs for the chrome hubcaps. I have been wrong before.

The track was Thunderhill Park Raceway about 80 miles north of Sacramento. It is owned and run by the SCCA San Francisico Region. We raced for school on the front half which is 1.9 miles with lots of turns. The full course is 3.0 miles long. I am looking forward to my first real regional race but need to do some more work on the car to be competitive. Take care.

Steve

Steve,

My bag as I measured wrong. I took the measurements tonight from the inside of the lips where the wheel sits and it is 4.5" wide. So the stock rims are indeed 4.5" wide as everyone stated. Sorry for the confusion. Still the 5-3/4" I measured last night does give us the correct backspace and offset. So those figures are still correct. Later.

Steve

Steve,

Thanks a lot. That makes sense. I suppose that the convention for measurement is inside to inside when stating wheel width.

So, to review, the stock wheels are 14" in diameter, 4.5" wide and have an offset of -0.625".

Again, Steve, thanks a lot. That was above and beyond the call of duty.

Steve

Yes, that pretty much sums it up. I need to go looking for some 15 x 6 rims for the race car this weekend. I have a spare front hub lying around so I will take that to make sure the hub clears. The offset/backspace measurements will come in handy to. Glad to help out.

Steve

Steve-
In all fairness to you, don't be very upset with yourself for measuring the wheel width wrong. 30 years ago, when these cars were "popular", there were a lot of wheel shops around that could take the narrow rim off the center, add a wider rim, at whatever offset you wanted, and weld it all back together (and they ran true). So you would still have the hub cap clips, but a wider rim. That's how they did "chrome reverse" rims. You can't just turn the wheel around and bolt it on backwards. Couldn't even do it with the '57 Chevy I had that had the stock wheels. My first set of racing tires were mounted on steel rims.

Today, I think most of those shops have gone the way of the dinosaur, what with the proliferation of alloy wheels over the years. "Back then" alloys were a relative oddity, kinda like steel wheels are today. In fact, in the early-middle 70s in LA, if you had alloy wheels on your 240Z (hard to find one even then with steel wheels), you couldn't run in the Stock Class. Ah, when "stock" meant "Stock". Anyway.

I wonder, would a factory-original Morgan+4 run in "Wood stock"? Hyuk, hyuk, hyuk!

Bucky

p.s. I finally found the original window sticker for my roadster , along with the paper plate and the hand-written temporary registration. I've been looking for this stuff for at least five years. I KNEW I hadn't thrown them away! At least now I know the VIN of what I'm looking for.

I did not feel too bad as stuff happens. It was good to find the offset an backspace numbers if nothing else.

So what was the VIN # of your car? Maybe we could post it some where on the website and someone may still have it. Take care.

Steve

I still haven't gotten stock size wheels and, as I was perusing the Datsuns.com site, I find this image:



Obviously, I'm getting my hopes up about where it says 5" wide wheels, changing to 5 1/2" wide after 1967. I now it's a pipe dream to think I can look for 5.5's instead of 4.5's, but I'd like to be sure about what this means.

I promise that sometime this evening, I'll measure my spare, which I'm pretty sure is a stock wheel. I don't know why I didn't manage it this weekend. I was thinking of it and just blew it off. Anyway, if anyone can think of an explanation for the width on this image, I'd really appreciate it.

Thanks,
Steve