Datsun Roadster Forum-311s.org

What kind of shop should I take my wheels to to get the center bore enlarged to 73 mm?

Just bought my roadster and the rear wheels have a 48 mm center bore. The fronts are 73mm.

Thanks

Why do you need to swap them ?
Modifying auto parts Is a big no no , even repairing a major component isn't anything a successful shop will do , leaves them open to a law suit
Many shops wouldn't turn a brake rotors anywhere close to minimum specs

A good general purpose machine shop can do it. An automotive machine shop generally has special machine tools that don't have the flexibility to handle such things(but they may). The last set that I did I mounted on the mill and used a boring head. You do need to understand the engineering side and make sure you do not reduce the strength.

I would never attempt to make that much of a change. I'd get the correct bore wheels.

I was hoping to have the center caps on all four wheels to match, which is the reason why I'm asking about enlarging the center bore.

I remeasured the center bore on the rear wheels and it is 67mm. The wheels are Rota RBs, 15 x 7. Just looking into the feasibility of having the rear wheels bored to 73mm versus eventually purchasing new wheels.

That is much better for sure. This is what mine looks like if that helps you at all. Still not endorsing it but if you do, find a good shop that can indicate on the center bore as well as off of the backside of the wheel flange where it mounts. Get either one wrong and the wheel is out of true.

Sticking it on a big lathe and clamping the rim may not be true.

If all you want is for the cap to fit you may not need to bore all the way through. I mounted them on the mill, indicated the center of the hole and squared, then used a boring head to open it up. It does need to be done properly, an angle grinder is not the answer.

So, now looking for opinions. Roadster came with Rota RB 15x6 +25mm upfront with 15x7 +20mm in the rear. If I replace the rear wheels with 73mm center bore wheels, which wheel size and offset would you recommend?

devauxmidwest wrote: Sat May 01, 2021 1:26 am So, now looking for opinions. Roadster came with Rota RB 15x6 +25mm upfront with 15x7 +20mm in the rear. If I replace the rear wheels with 73mm center bore wheels, which wheel size and offset would you recommend?

My advice, with the Rota brand wheels, would be to stick with the same dimensions front and rear. I don't understand why they offer staggered width/offset packages for our cars; the wheels are visually identical and there is no aesthetic difference with their 15x6 vs 15x7 wheels.
Can any of you Rota owners chime in on the rationale for the 15x6/7 stagger on a stock-flared car? Especially if you run the same tire size all around?

From a member in the Wheel/tire section: viewforum.php?f=34

Rota RB Hyper Black 15x6 20 offset
Yokahama 195/55/15
I ordered the 73mm, but they did not fit the front hubs. Had a local machine shop bore the inside of the hub to fit.

From member "Devo"

joe fremeau wrote: Tue Apr 21, 2020 9:45 am Hi. Wondering if someone could help me, looking to buy a set of Rota rb. 15 x 7 wheels for my 67 1/2 . What would the best offset be they offer +4. + 12 and +20 without rolling the fenders Thanks stay safe Joe

Here are the Rota RB 15X6 on my '66. +20 offset, Large Caps. 195/55R15. I've since put on 1 inch lowering springs in front and body sits right down on the tires with no rubbing even in spirited driving.

[/quote]

Here are some shots after the lowering springs with zoom in.

I was wondering the same thing about why different wheel widths when I bought the car.

Mike Young thought folks did that so that the tires lined up better front to rear.

I put the 15x6 wheels on one side, and looking from the rear of the car, it's more noticeable that the front tire sticks out more than the rear tire. With x6 on the front and the x7 on the rear the tires "look" like they stick out the same amount in the fender wells. I've always ran the same wheel and tire size front and back. Pretty sure the factory wheels were the same size all the way around.

If I keep the 15x6 +25mm on the front what is the recommended offset for a 15x6 wheel on the rear?

You bought a car from Mike Young?
Please post pictures!

devauxmidwest wrote: Sat May 01, 2021 1:32 pm I was wondering the same thing about why different wheel widths when I bought the car.

Mike Young thought folks did that so that the tires lined up better front to rear.

I put the 15x6 wheels on one side, and looking from the rear of the car, it's more noticeable that the front tire sticks out more than the rear tire. With x6 on the front and the x7 on the rear the tires "look" like they stick out the same amount in the fender wells. I've always ran the same wheel and tire size front and back. Pretty sure the factory wheels were the same size all the way around.

If I keep the 15x6 +25mm on the front what is the recommended offset for a 15x6 wheel on the rear?

These cars have a wider front track than rear, so they look weird viewed from the rear or rear 3/4 angle.
I wouldn't run the +25mm offset. If you must, put a 10mm spacer on it.
For the front and rear, anything close to +15mm offset is ideal.
Things change depending on the model year with respect to fender flares. Early cars with smaller flares will not accept the wider wheels as well as later models years.

Member Mic-Velo actually runs a staggered setup on his '68 SRL:
"MicVelo"

15x6 +20 Front
15x7 +20 Rear
195/55-15 Dunlop Direzza DI

Alvin wrote: Sat May 01, 2021 1:16 pm From member "Devo"

joe fremeau wrote: Tue Apr 21, 2020 9:45 am Hi. Wondering if someone could help me, looking to buy a set of Rota rb. 15 x 7 wheels for my 67 1/2 . What would the best offset be they offer +4. + 12 and +20 without rolling the fenders Thanks stay safe Joe

Here are the Rota RB 15X6 on my '66. +20 offset, Large Caps. 195/55R15. I've since put on 1 inch lowering springs in front and body sits right down on the tires with no rubbing even in spirited driving.

Here are some shots after the lowering springs with zoom in.



[/quote]

I was offered the 15X6, 15X7 combo by 18racing when I purchased mine. I was told the 15X7 was for up front with the greater offset. I declined and am glad I did. I run the 195/55R15 all around on 15X6 rims. They are perfect front and rear. With the way my car sits, I have about an inch of clearance from tire sidewall to the inner wheel well in the rear. Up front, the tires stick out about an inch from the flare and it looks great. No tire rub at all. Wheel came with the large cap, 73mm bore.

I’d recommend just like factory, having the same rim on all four. For engine swaps with added power, then 15x7 +10-15mm rear; 15x6 +15mm front. Of course you can vary a bit to your liking and the tire cross section width.

I’m doing an engine swap so I’m using:

15x7 +30mm rear (+30mm only works because I’ve moved the leafs inboard 1” and trimmed (and welded up) about 5/8” of the frame lip to run 225/45/15s (no flares).

15x5.5 +15mm on front. From what I see on this rim, the 15x6 +20 that some folks are using, must be getting pretty close to the max (w/o mods) as clearance to the inside goes.

As for the caps you’d have a main bore, larger than the cap bore and then the through bore which is the last small bit for the cap size. You might find same or very similar caps in a couple different cap bores if that’s needed.

One thing to watch for when measuring or test fitting tires (especially rears) is that the body may not be centered on the chassis. Quite a bit of leeway is provided there. so if you test one side and tires are close but ok, it may not be ok on the other side.