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Discussion Starter #1
Have you guys ever seen anyone with Ruff 278s on a VR4?

I had these on my G35 before and just got the VR4 not too long ago ... I was wondering if these would be bad to run on the Vr4 seeings how they are 225-45-18 in the front and 245-45-18 in the back?

i couldnt find that calculator anywhere that told me the percent difference or watever so please dont bash on my lol


thanks guys any insight would be much appreciated
 

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|RLII Photography|
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Here's the tire size calculator, Google keywords "tire size calculator"
http://www.miata.net/garage/tirecalc.html

The front tires will be making 777 revolutions per mile while the back tires will be making 756 revolutions per mile. This is BAD and will eventually cause your center viscous coupling unit (VCU) to fail. On a staggered setup, you need to shoot for less than ~5 revolutions per mile difference between the tires.

As far as the wheels fitting your car, that all depends on the width, pad height, and offset. I would say though that there is a high probability that they will not fit with a general G35 offset, at least the front wheels will most likely not clear the calipers. Or if the wheels fit, they will stick out significantly from the fenders.
 

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MrWallyvr4
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Help me figure out why tire width would make the tires RPM change? Thanks in advanced I never under stood that.

I used to run RUFF rims on my VR4, I think they were 18x9.5 in the front and 18x10.5 in the rear. I had to run 20mm spacers on both to clear the calipers.
 

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crap, i have 245/35/19 in front and 275/30/19 in the back, front is 783 and rear is 791, is this going to be bad? i checked it on another site and its a 7 rev/m difference instead of 8.
 

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Help me figure out why tire width would make the tires RPM change? Thanks in advanced I never under stood that.

I used to run RUFF rims on my VR4, I think they were 18x9.5 in the front and 18x10.5 in the rear. I had to run 20mm spacers on both to clear the calipers.
Quick math lesson

245 is the width in mm. The second number 45 in this case is the percentage of width that the sidewall height is.

245mm = 9.65 inches wide

9.65 x .45 = 4.34

(4.34 x 2) + 18 = 26.68 inches tall

That being said the 245/45/18's are too tall and wont work. Stock is 25.7. Youd need 245/40/18's.

Comparison

225mm = 8.86 inches wide

8.86 x .45 = 3.99

(3.99 x 2) + 18 = 25.98

There is almost 3/4 of an inche in diameter. That will fry a VCU in a hurry. But the 245/45 wont even fit and 225 on a VR4 is retarded.
 

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crap, i have 245/35/19 in front and 275/30/19 in the back, front is 783 and rear is 791, is this going to be bad? i checked it on another site and its a 7 rev/m difference instead of 8.
You realize the 275/30's are shorter than the 245/35's dont you?

You are looking at about 1/4 inch of difference.
 

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You realize the 275/30's are shorter than the 245/35's dont you?

You are looking at about 1/4 inch of difference.
5mm is not 1/4 of an inch, its a little less than 7/32th. Front is 9" wide and rear is 9.5" wide, i just got them yesterday, bought spacers today and new hub rings...
 

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I did the math. Look at the tire calculator too.

the 245/35's are 25.75
the 275/30's are 25.49

EDIT: Again if you look at my first post the second number in the tire is a percentage of the width that ends up determining the sidewall height.

EDIT again: In metric it is 6.5 mm difference in height. I am not determining circumference here though its easy enough to do once you have diameter.
 

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I checked the tire spec's and its still 7 more revs per mile, i did a quick search and found some people mention the same setup that i have but not sure if anybody used it or not.
 

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Somebody has had to run this setup, i wonder if two more revs per mile do any harm? Is there any real evidence of this? Did somebody damage the vcu after more than 5 revs, I wonder where vr4rob got his information, would be nice to see and read up.
 

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Discussion Starter #17
well thanks guys ... the only reason i was wonderign cause i already had the rims and if they did fit they look nice on the car ... i guess im just gonna sell these and get some 18in fn01 ...thanks -derek
 
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