30s cost more, hence why soo many 35 are sold...

 

could be the sidewall. 30s in the rears..unless ur not lowered u can pull off the 35s

quick question:

why do so many people recommend
the 245/35s fronts, with 275/30 rears?? is that the same diameter? front n rear...
compared to 245/30s? does the 245/35 make the fronts bigger? or just about the same? (sidewall)/overall diameter.

 

Dunno, maybe one of the tire sponsors can chime in.

 

i just bought my staggered set up from here:http://wheelstudio.com/ they automatically had 3 or 4 different tires set-ups for our car. then i went to here: http://www.miata.net/garage/tirecalc.html and here: http://www.tiresizecalculator.info/
to pick the best set-up for my 20's. now i like all that aggressive stuff, looks great but i dont have the financial backing to readily just purchase tires so i got the size that kept my "G" riding nice and my speedo accurate (as can be) without having it recalibrated. hope these help you choose the correct size for you.
by the way, i am running : Staggered Tire Option 2 : Front: 255/35R20 Rear:285/30R20, no rubbing but not dropped...yet

 

The more I hear, the more I think I only need to change the back. 275 30 20's looks like the choice. I'll be pissed if that doesnt solve it!

 

Got the 275 30 20's.....NO rubbing!

 

great, made a big difference huh?

 

Yes sir....thanks for the help folks!

 

huh? 255/35 increases your front tire overall diameter by 1.06" compared to stock 18 setup. why would it suggest you do that? the proper size is 255/30.

(The math, if you want it so you never mess up again:
stock: 225/45/18 --> 225mm*0.45 = 10.125cm = 3.986"
[(2*3.986") + 18" = 25.972"

20's: 255/30/20 --> 255mm*0.30 = 7.65cm = 3.012"
[(2*3.012") + 20" = 26.024"

255/35/20 --> 255mm*0.35 = 8.925cm = 3.513"
[(2*3.513") + 20" = 27.028"

as you can see, with 255/35 your front diameter gets changed by alot compared to stock

 

actually, mine came on the stock 19" wheels. 225 40 R 19 was the stock tire size all the way around. i just plugged it into the calculators that i posted to find the 20" rim, tire set-up that kept my diameter and tire size accurate as possible so my speedo reads correct.
but looking at your math i am a lil confused the first number (255) is the width across the tire tread. the second number (30/35) is the height of the sidewall. the third number (20) is the hole in the middle of the rubber for your rim. all that said, i cant figure out why you would be multiplying the width times anything because that has nothing to do with the ride height of the tire/car as it is sitting in your wheel well. i mean, if your trying to figure out the area inside the tire maybe but for the life of me i can not figure that part of your calculations out. as far as i can see those numbers have nothing to do with what your trying to figure out unless you are talking about how far the tire is being pushed out from where it will be mounted on the rotor, then its a lot of other things you have to know like the depth of the wheel well ect...
just seems that you confused the issue or i have just simply over simplified it? let me restate my point right quick: how does the width/depth of the tire across the tread have anything to do with converting from an 18"/19" rim to a 20"? besides the width have to fit to the rim width. can someone please help me to understand my math cause i never wanna mess up again...

 

i asked a friend of mine about my hunch and he confirmed, one of the main reasons for recommending the 35 in the front 30 in the rear is simply this: front of the car carries the weight and only really moves if you hit a pot hole. the rear moves and your weight changes you put stuff in the trunk, ppl in the back, the smaller in the rear allows for the movement. (Basically)

 

Well, whatever the reason 275 30 20 is the charm!

 

4sho

 

you are misinformed on many things here. First of all, your car did not come with 225/40/19 all around stock, it came with 225/40/19 and 245/40/19. The width of the tire comes into play when upsizing from 18/19" to 20" because the aspect ratio is a percentage of the tire width, and is chosen based on the overall diameter of the stock tire size. 225/40/19 is equal to a 245/30/20 or 255/30/20. If you wanted to use a 225 width in the front on a 20" wheel, then you would want a 225/35/20. If you wanted to run a 275 in front, then you would have to drop down to a 25 series tire to match the oem diameter, 275/25/20

 

So what combination for 20" on 350z H tein? 245/35/20 F 275/30/20 R OR 245/30/20 R 275/30/20 R?