Datsun Roadster Forum-311s.org

Thanks for looking out for me. I'll check the backspace when I get home.
In general, do the tires tend to rub because they are too wide or too tall? In other words, will I reduce the rubbing issues by going with a 195/60 because it is shorter (but wider) or a 185/65 because it is thinner (though taller)?
Anybody know the total height of the stock wheel/tire combination from the factory, so that I can calculate the distortion to my speedometer for a given tire size? I can't seem to find that information on the main site or by searching.

Andy, nice wheels, you mentioned the wheels are from a Z car, if you also got the lug nuts with the wheels they will be for a 12mm stud instead of the 7/16" that our roadsters have, just a word of caution.. Bill

Conner wrote:Anybody know the total height of the stock wheel/tire combination from the factory, so that I can calculate the distortion to my speedometer for a given tire size? I can't seem to find that information on the main site or by searching.

99% sure it's in the ballpark of a 175/70-14 or 185/70-14.

No math necessary if you go here...

At that site you can plug in your stock tire size, your new tire size, and it tells you the size/diameter difference and the speedo calibration differential... I hate figuring out the rollout...

Bill Cole wrote:...lug nuts with the wheels they will be for a 12mm stud instead of the 7/16" that our roadsters have, just a word of caution.. Bill

Handy information to have... How are folks running the ZX rims then? Drilling out the hub for 12mm studs?

Thanks. Didn't come with lugnuts and I plan to use the stock ones if they work or located some that do. I just measured the backspace and it appears to be 3".
The overall width of the wheel, from lip to lip is about 6 3/8" and the surface on which the tire rides is 5 1/2". So I think that puts the offset at 3/16" or almost +5 mm, which I think is the wrong direction (the mounting surface is closer to the inside of the wheel). I think there is probably enough variation in the cars that I just need to get them on and see if they rub. But I would like to choose a tire that minmizes the likelihood that they do rub.

Conner wrote: So I think that puts the offset at 3/16" or almost +5 mm

In wheel parlance, that's -5.

which I think is the wrong direction

Sounds like it...

But I would like to choose a tire that minmizes the likelihood that they do rub.

If you go tall, like a 175/70-14???

And I always say if it's not rubbing, it's not low enough...

Have you rolled your rear fender lips? If not, you'll want to while you have the wheels off.

The issue with the factory Z wheels (not the dealer option ones) is that they use a larger diameter shank on the lug nuts. There are 3 solutions that have been tried.

1) remove the stock studs and find some 12mm studs that will fit and replace them all

2) get standard aftermarket lugs and make/buy (Mike Harper has some) bushings to take up the extra space.

3) go to www.wheelcomponents.com and just buy the right aftermarket lugs. (.73 diameter shank versus .60 iirc)

If you have dealer option wheels (like the 5 slots), then any wheel shop will have generic "mag wheel" lug nuts which will work.

Have fun!

I always get negative and positive offset mixed up!
Haven't rolled the fender lips yet. Yes, the wheels are off, but so is the body at this point.
I'll be running Mike Young comp springs up front, stock early-style leaves in the rear.

datsunfreak wrote:And I always say if it's not rubbing, it's not low enough...

My car doenst rub.... have you seen it??

Import_sounds-of-mid-GA wrote:My car doenst rub.... have you seen it??

Mine doesn't rub either, but it took alot of work to get there...

Andy, I will check my tire size for reference when I get back to the US...

Bill is correct, you will need new lugnuts (7/16-20) shoulder style, not cone. I forget the length, but get the longest that fits in the wheel. I suggest McGard, a bit more expensive, but very, very nice and well worth the $.

All slotted mags use the standard lug diameter, you won't run into the issue Sid mentioned (that is a pain), I think that was limited to Nissan wheels supplied by the factory, not dealer wheels. That is a good word of warning to anyone that wants to use the "iron cross" Z wheels!

datsunfreak-that is a cool tire geometry calculator! You can get both 12 and 7/16 lugs in the proper diameter for most wheels, only the odd factory Z wheels have the different lug diameter. Sid listed the fixes...Of course, Z, 510 and roadster wheels all want slightly different sizes.

Andy-too bad those are offset that way. If I remember, my offset is also 5mm, but mine moves the wheel inward. With the tire size I will send, they rub in corners with bumps. Again, they do not rub on the lip, but higher up in the well on the rear. They will work fine on the front.

I have been considereing a panhard bar, maybe that will eliminate the side slop enough to keep the tires off of the fender.

TR wrote:I have been considereing a panhard bar, maybe that will eliminate the side slop enough to keep the tires off of the fender.

Don't forget that with radial tires (as opposed to bias-ply, which were the factory tire), under cornering forces, that the tread will move in or out in relation to the wheel. A panhard bar won't help with that sitution.

Huh, whaaat? Bias ply's!?

I don't know if the rubbing is caused by axle movement or tire flex or a combo. Adding the bar would be an easy way to rule out one of the players...

Conner wrote:will I reduce the rubbing issues by going with a 195/60 because it is shorter (but wider) or a 185/65 because it is thinner (though taller)?

Ive had 185/60 and 195/60 on the back... they both fit perfect.
195/60 on rear

185/60 on rear