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Am original owner of '74 260 z that is in need of new wheels and tires. I am trying to decide whether to go to a 14x7 inch custom wheel or stay with the 14x6 inch size. I like the 14x6's but most of the new wheels are recommending 14x7. If I go up in size, what size tire should I get that would give me the same relative look that my 185/70/14's give me now. They don't recommend that tire for a 7 wheel. Should I go to a 205/?/14? or 195/?/14????? Wish I could see them on before I buy them. What are the down sides to a 14x7?
 

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I just have the original wheels on my car, but from talking to others I get the feeling if you run a 14X7 you MIGHT run into clearence problems with the struts. Unfortunately if you go with a wider wheel/tire it moves more inward towards the strut. This can sometimes be fixed with spacers, but not always. I haven't done any of this myself, just telling you what I have been told by others.
 

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> Am original owner of '74 260 z that is in
> need of new wheels and tires. I am trying to
> decide whether to go to a 14x7 inch custom
> wheel or stay with the 14x6 inch size. I
> like the 14x6's but most of the new wheels
> are recommending 14x7. If I go up in size,
> what size tire should I get that would give
> me the same relative look that my
> 185/70/14's give me now. They don't
> recommend that tire for a 7 wheel.
> Should I go to a 205/?/14? or 195/?/14?????
> Wish I could see them on before I buy them.
> What are the down sides to a 14x7?

Carl,

Here's a quick explanation of tire sizes and what to expect.

The first number is the size of the tire accross the tread, including the widest point of the sidewall, in mm. So a 185/?/? is 185mm wide at its widest sidewall dimension. The next number is the aspect ratio or percentage relating to the height of the tire. A 70 series tire is 70% tall as it is wide, a 60 is 60%, etc. So your 185/70/14 tires are about 129.5 mm tall, from the top of the rim to the top of the tread.

So if you want to stay with the same aspect ratio, get a 215/60/14 tire-- 215 x .6 = 129. You can move up or down a few mm without adversly affecting your speedometer. In fact, I think in my owners manual for my 78 it calls out 195/70/14s. So if you're running 185/70s you're actually a little undersized now-- provided they used the same wheel tire sizes.

I ran 225 and 235 60s on my 14 wheels for many years. You'll notice a big improvement in road holding, (provided you choose a high performance tire) but it becomes increasingly difficult to use your power steering by armstrong at parking speeds.

I've recently moved up to a 15 inch wheel and love the difference in road feel. If you're going to buy new wheels, I'd recommend going to a 15 or 16 inch wheel. The difference in feel is noticeable and you'll have many tire sizes and options available to you.

Hope this helps.

Matt

PS. Go check out tirerack.com You'll be able to shop and compare tire makes, sizes, prices, specs, etc. Very helpfull.
 

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Re: Tire Plus-sizing

The overall stock diameter should be your goal. I have an 83zxt with 15 inch wheels. If I look up the size at my store (Sears) I get 205-70-15 for turbo and 205-70-14 for non turbo. If you use the below formula, you can atttain a pretty good fitment in a larger size regardless of the size of the rim. If you take a 185-70-14 size it's overall diameter or heigth from street to top of tire is: ( (185 x 2 x .70) / 25.4 ) + 14 = 24.19 inches. This is pretty close to what it would be anyway. Tire sizes do vary by maker. The general rule in going up in size is, for every 10 mm of width you increase, decrease the aspect ratio 5 mm. So go with a 195-65-14 and get 23.98 inches. 195-65-15 gives 24.98. 205-60-14 gives 23.68. 205-60-15 gives 24.68. I agree that the tire size you are running is small I think my 240 was a 195-70-14. My 83 is running a 215-60-15, BOUT 25.1 Inches-- the next tires I buy will be a 215-65-15 ( 26 inches) so that 1st gear won't wind out so quickly. Hope this helps. What was your question again?!
ps: Centerline is said to build lots of wheels in customers desired offsets.
 

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There is another route...

> ps: Centerline is said to build lots of
> wheels in customers desired offsets.

These babies might be the only route to getting a modern offset wheel. They reccomend using only 1.25in thick units on the Z (just called em yesterday as a matter of fact) but I think you could probably safely use 1.5in ones safely. The dude I talked to said they have used them on lots of high HP american cars and trucks (such as full size sport-ute's doing heavy towing) with no problems. (now as for how much of that is marketing I dunno) They run $320 for the set though (ouch!) and the price goes up for thicker ones. Anyways, I believe adding an extra inch or inch and a half should be enough to let you run a fwd offset wheel, but it probably would involve some test fittings you could also switch to a 5 lug pattern this way (though since it's still bolted to a 4 lug hub I can't imagine any real difference strengthwise) Anyways, I'm considering a set myself because I'd really like to run 17's on the Z and unfortunately short of paying HRE 600 plus bucks a wheel to custom make em, this looks like the next best alternative. *sigh* is nothing ever inexpensive that's really cool?
 

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> Carl,

> Here's a quick explanation of tire sizes and
> what to expect.

> The first number is the size of the tire
> accross the tread, including the widest
> point of the sidewall, in mm. So a 185/?/?
> is 185mm wide at its widest sidewall
> dimension. The next number is the aspect
> ratio or percentage relating to the height
> of the tire. A 70 series tire is 70% tall as
> it is wide, a 60 is 60%, etc. So your
> 185/70/14 tires are about 129.5 mm tall,
> from the top of the rim to the top of the
> tread.

> So if you want to stay with the same aspect
> ratio, get a 215/60/14 tire-- 215 x .6 =
> 129. You can move up or down a few mm
> without adversly affecting your speedometer.
> In fact, I think in my owners manual for my
> 78 it calls out 195/70/14s. So if you're
> running 185/70s you're actually a little
> undersized now-- provided they used the same
> wheel tire sizes.

> I ran 225 and 235 60s on my 14 wheels
> for many years. You'll notice a big
> improvement in road holding, (provided you
> choose a high performance tire) but it
> becomes increasingly difficult to use your
> power steering by armstrong at parking
> speeds.

> I've recently moved up to a 15 inch wheel
> and love the difference in road feel. If
> you're going to buy new wheels, I'd
> recommend going to a 15 or 16 inch wheel.
> The difference in feel is noticeable and
> you'll have many tire sizes and options
> available to you.

> Hope this helps.

> Matt

> PS. Go check out tirerack.com You'll be able
> to shop and compare tire makes, sizes,
> prices, specs, etc. Very helpfull.

Actually they used different tire sizes on the 260 to the 280. I bilieve his tires are actually the correct size for the 260Z, the 280Z moved up to 195/70/hr14 tires in 1975. I just got new tires about 2 weeks ago for my 75 280Z from the tire rack. They are dunlop D60's, size 195/70/14 h-rated, they cost only $44 a piece and so far I am very impressed with them, especially for such a good price!!

good luck,

James.
 

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Re: There is another route...

> These babies might be the only route to
> getting a modern offset wheel. They
> reccomend using only 1.25in thick units on
> the Z (just called em yesterday as a matter
> of fact) but I think you could probably
> safely use 1.5in ones safely. The dude I
> talked to said they have used them on lots
> of high HP american cars and trucks (such as
> full size sport-ute's doing heavy towing)
> with no problems. (now as for how much of
> that is marketing I dunno) They run $320 for
> the set though (ouch!) and the price goes up
> for thicker ones. Anyways, I believe adding
> an extra inch or inch and a half should be
> enough to let you run a fwd offset wheel,
> but it probably would involve some test
> fittings you could also switch to a 5 lug
> pattern this way (though since it's still
> bolted to a 4 lug hub I can't imagine any
> real difference strengthwise) Anyways, I'm
> considering a set myself because I'd really
> like to run 17's on the Z and unfortunately
> short of paying HRE 600 plus bucks a wheel
> to custom make em, this looks like the next
> best alternative. *sigh* is nothing ever
> inexpensive that's really cool?

Another knowledgeable user of this forum mentioned several weeks ago that Zcars don't like adapters very much. You might check the archives for a message about front end vibrations, wheel balancing problems, or some such thing.

I can attest to his statement. I have four to five lug adapters all the way around my car and I'm taking them off! Care to buy them cheap? make me an offer. The front tires have been back to the shop for balancing over and over again but they're never right. I took the wheels off of my '93 ZX and put them on (modern offset) and it still wasn't right. These wheels and tires have absolutely NO vibration on the ZX. By the way I need new bearings on the back. This is probably due to the adapters and the large offset on the wheels

I plan to buy four lug wheels with the correct back spacing. By the way, I don't remember how thick these adapters are but they're at least an inch, but not much more.

Lee
 

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Re: There is another route...

Are yours aluminum or steel? I would think that the lighter they are thel less problems you'd run into. Also, have you been having the wheels balanced with the adapters bolted onto them at the time? I have a couple other ideas I'm tossing around mentally with them, but I'd like to find this stuff out first.
 

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> Am original owner of '74 260 z that is in
> need of new wheels and tires. I am trying to
> decide whether to go to a 14x7 inch custom
> wheel or stay with the 14x6 inch size. I
> like the 14x6's but most of the new wheels
> are recommending 14x7. If I go up in size,
> what size tire should I get that would give
> me the same relative look that my
> 185/70/14's give me now. They don't
> recommend that tire for a 7 wheel.
> Should I go to a 205/?/14? or 195/?/14?????
> Wish I could see them on before I buy them.
> What are the down sides to a 14x7?

Hi Carl,

I have now amassed 5 sets of wheels for my 71 240,
set of 14x6 5 slots
set of 14x7 Enkie gold mesh
set of turbine style in millimeter size (390mm)
set of 13x7 ARE
set of 15x7 ARE

Its all very frustrating I know. Best answer I can give is:

a: get a set out of the junkyard (there are a ton if your willing to look)

b: Any wheel with a 4X4.5 bolt patern, close to zero offset, and 7 or under width will work for you.

c: As for tire size, just measure the stock tire diamenter on your car, and take a tape measure with you when you buy tires, keep the overall diameter plus or minus a half inch of stock and your gearing and speedo won't change much.

PS if your really ambitious, find a machinist and get some 1.5 aluminum billet spacers made.
8 holes...
4 counterbored and tapered to bolt on to the stock studs with the stock nuts, and the other four for new studs to be pressed through the back of to extend out and accept the wheel.
Turns out Honda Civic wheels have the same bolt pattern with a 1.5 inch offset. And there are hundereds of wheels available for the civic. Use caution for this though, because if not designed right the spacers might not work or worse, fail while on the road. Good luck,

Ian
 

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Try going to disount tire. Not only do I work there I also know that every store will go out of there way to make a sale. We would even test fit the wheels or tires that you would like to try.That is just a suggestion.
 

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Re: There is another route...

> Are yours aluminum or steel? I would think
> that the lighter they are thel less problems
> you'd run into. Also, have you been having
> the wheels balanced with the adapters bolted
> onto them at the time? I have a couple other
> ideas I'm tossing around mentally with them,
> but I'd like to find this stuff out first.

I'm not sure if they're aluminum or steel. I'll have to check.

They were balanced WITHOUT the adapters on them. But getting the adapter on and off is a real female dog. The only set of wheels I have for this car a two-piece type. If I could buy the four lug center section from the manufacturer I think I could change them out myself. This would work if the back spacing remains the same, but there appears to be plenty of room in there. I think that the only reason for the adapters was so the original owner could use the five lug wheels. If that's the case there may be no center pieces with a four lug pattern for me to buy.

I'm going to start working on the car in March. I'll let you know what I end up doing then.

Lee
 

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Re: There is another route...

> I'm not sure if they're aluminum or steel.
> I'll have to check.

> They were balanced WITHOUT the adapters on
> them. But getting the adapter on and off is
> a real female dog. The only set
> of wheels I have for this car a two-piece
> type. If I could buy the four lug center
> section from the manufacturer I think I
> could change them out myself. This would
> work if the back spacing remains the same,
> but there appears to be plenty of room in
> there. I think that the only reason for the
> adapters was so the original owner could use
> the five lug wheels. If that's the case
> there may be no center pieces with a four
> lug pattern for me to buy.

> I'm going to start working on the car in
> March. I'll let you know what I end up doing
> then.

> Lee

I'm kinda thinking you have the crappy wavy style ones they are steel and don't look all that structurally sound (as in the kind sold at checker/autozone/pepboys etc) I actually could care less about what lug pattern I run provided I have a better choice of wheels. I saw somebody posting something here (or maybe on autoforums can't remember for sure) that they had spacers 1.5 inches thick that allowed them to run honda lug pattern which is fine with me as there are the proverbial buttload of wheels available for that pattern/offset. It's somewhat of an expensive gamble, but I think It'll work. Nevertheless, keep me posted on how yours works out. (and if you try getting the wheels balanced with the adapters installed let me know as well) At least these don't look like they'd be difficult to balance this way, it would just be a little more work torquing them on before balancing and removing them (marked so you don't move them from the balanced postition) before yet again installing them on the actual hub, and then installing the wheel back onto the adapter (course finding a tire shop that won't get pissy about doing it may be another matter entirely)

Don't know if the manufacturer of your wheels will sell the center sections but hey it's definitely worth a try. Good luck, on your endeavor.

I've kinda been tossing the idea around of taking some machining classes at the local community college, maybe I'll just make my own adapters, or better yet billet hubs that change the offset. I think this would be feasable in theory at least, cost may be an issue however but it's something worth looking into.

Good luck

--Brian aka Zebra
 
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