SparkleCityHop

iTrader: (30)

I have tried to educate myself as much as possible with the ample information available in the forums. It has gotten me this far, but I'm a noob when it comes to my Zcar, so I wanted to get some input and find out if the way that I have gone about choosing my wheels "makes sense".

I just purchased a set of Motegi Togue Gunmetal 19" wheels for my '04 Silverstone Roadster 6MT (daily driver). I purchased a staggered setup with 19x8 for the front and 19x10 for the rear with a +30 offset. The car had the stock 18" wheels with +30 offset and 225/45R18 tires on it when purchased.

I wanted to provide info on how I used the calculators and others' advice in deciding on my tires - maybe it will help others in the future or maybe someone more knowledgable than me can tell me if I went about it all wrong.

This probably isn't the best way to go about deciding, but it's what I was able to come up with:

1) Determine tire widths that will fit my new wheels
2) Find out what tire sizes in these widths are close to factory diameter
3) Find out which tire combinations front & back keep the diameter ratio close to each other
4) Look at availability of different options & pricing
5) Choose my tires based on personal preference and the above info
6) Determine spacer/offset needs

I used this calculator for comparision and "Rim Width Range" for different tires - http://www.1010tires.com/TireSizeCalculator.asp
I used this simple calculator at first for diameter comparisons - http://www.miata.net/garage/tirecalc.html
I used this calculator for calculating spacer/offsets - http://www.e90post.com/forums/showthread.php?t=293840

For my 19x8 front and 19x10 rear wheels, the calculators tell me the following wheels will fit:

19x8 Fronts widths:205-255 (8 in = 205mm)
19x10 Rears widths:255-295 (10 in = 255mm)

I want to err on the fatter/wider side, so I'm looking at 235-255 for the fronts and 275-295 for the rear.

Stock Wheel Diameter for reference:
225/45R18 STOCK 26.0 DIAMETER

Combinations used/suggested by others on the forums:
245/35R19 275/35R19 25.8/26.6 DIAMETER (41 @ $149)(23 @ $188)
235/35R19 285/35R19 25.5/26.9 DIAMETER (56 @ $129)(30 @ $201)
(both have a significant diameter difference between front & back, which makes me think that TCS may not be happy with the difference in diameter front to back)

The sizes that seem closest to stock diameter look like:
245/35R19 285/30R19 25.8/25.7 DIAMETER (41 @ $149)(13 @ $203)
245/35R19 295/30R19* 25.8/26.0 DIAMETER (41 @ $149)(23 @ $208)
*Likely too large for the wheel.

If I want to go with a larger profile (higher profile = less risk of potholes damaging my rims, etc. - taller than stock) and still keep the diameter ratio between front and back happy, it looks like I can consider:
245/40R19 285/35R19 26.7/26.9 DIAMETER (52 @ $105)(30 @ $201)
255/40R19* 295/35R19 27.0/27.1 DIAMETER (38 @ $163)(1 @ $287)
*Likely too large for the wheel.

NOTE: The numbers in the parenthesis are how many different choices there are on TireRack.com for that size tire and the price of the lowest option (since price and number of available options is important too).

My first choices in order of preference based on my calculations:
245/40 285/35 - A good choice if I don't mind my speedo reading slow by about 3.4%. Good ratio, lot of options, good starting prices)
245/35 285/30 - The safest choice based on fitment & similar diameter. Speedo will read fast by around 1.5%.

I'm thinking about going with the 245/40s up front and 285/35s in the rear. I have searched the forums and everyone's advice has been super helpful and Again, I just wanted to post this in case there is anything that I may not have thought about, etc - or in case this thread may help someone in the future that is trying to decide which size wheels to use on their new rims.

Also, as far as spacers go, the factory wheels are +30 and so are the ones I've purchased. Since I'm keeping the approximately the same width in the front (going from a 225 to a 245), so they should end up looking similar to how they do now since I'm only adding 10mm on each side of the tire. In the rear, I'm adding 60mm total (going from a 225 to a 285), 30mm inside and 30mm outside which it looks like should clear no problem without a need to roll my fenders, etc. However, if I want the fronts to be flush with the backs, it seems to me that I will need 20mm spacers for the front (30mm back - 10mm front).

Thanks in advance for any opinions/advice!

terrasmak

iTrader: (8)

Return the wheels and get something wider up front or 245/35 front and 275/35 rears would be the common size for you.


I would return the wheels.

SparkleCityHop

iTrader: (30)

Is there a reason why I should avoid an 8 front and 10 rear?

I ask because I like the wheels and I like the staggered look of the 8 front and 10 rear. I'm not looking for what is common, but what I prefer. I was looking for helpful advice in how to pick the appropriate tires for the wheels that I have chosen, and for comments/advice on whether or not I have overlooked anything in the way that I chose my tires.

If there is a problem/issue that I don't understand or know about by running the 8/10 setup, like I said, I'm just trying to learn here.

Thanks for your input/advice.

SparkleCityHop

iTrader: (30)

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Spike100

Good question, and thanks for providing detail.

You can run these wheel widths (8” front and 10” rear) with no problems. The offset on your new wheels is fairly conservative. That means you can go with a moderately wide tire in the rear and not worry about fender-rubbing even if you drop the car slightly.

Front: 245/35-19” is a good size for your fronts with the 19x8” wheels you just purchased. Since this is a DD, 245 in the front is a practical choice and certainly won’t disappoint you.

Rear: Your new rear wheels (19x10” with 30 offset) have a versatile size that accepts a broad range of tire widths. You could do any of the following:

• 275/35-19”
• 285/35-19”
• 295/35-19”

These sizes work for your rear tires and won’t mess-up your car’s electronics.


Additional comments about 295mm on the rear:

• If you go with a 295mm tire, you could use a 30 series (295/30-19”), but you will have a noticeable fender-gap that you could solve with a drop (1/2” would be plenty).
  
  
• 245mm (about the maximum that fits your fronts) with 295mm is a significant difference front-to-rear. If you want 295mm on the rear, I would do what terrasmak suggests and get different wheels (wider front wheel).

Just some thoughts,

--Spike

davidv

iTrader: (2)

I think you got it. TCS is much more friendly with tire sizes than VDC. You have lots of flexibility.

Be careful deviating from OEM overall tire height. That will alter rear axle ground clearance. Not advisable.

SparkleCityHop

iTrader: (30)

You mentioned avoiding a large difference between the widths of the front and rear (i.e. 245/295 setup) and recommended against this as terra did. Is this because of handling issues, tire wear issues, etc? or is it just because of the look?

If I go with a 245 front and 285 rear, is that still a concern?

Thanks, all of your advice is EXTREMELY helpful.

Spike100

^^

What are you saying? ...What does "ground clearance" have to do with this?

--Spike

Spike100

If I had your wheels (19x8” front and 19x10” rear with 30 offset), I would mount these tires:

• Front: 245/35-19”
• Rear: 285/35-19”

That wheel /tire setup will look great and be fun to drive. That’s a very good setup for a DD (much better than most people have). It will handle much better than your stock 225 F/245 R.

Do it… do it now.

--Spike

SparkleCityHop

iTrader: (30)

Spike-

What will be affected with a large difference between the front and rear widths?

Spike100

245mm front with 285mm rear isn’t that much difference. In fact many of the “exotics” are configured with a 40mm or greater difference front to rear. Notice that difference is even greater in Formula racing cars.

245mm is a good width for the front on a Z when you consider the car’s weight and its suspension design. This width provides fast turn-in without introducing bump-steer, a heavy steering-feel, or excessive strain on the stock front-end components. This is certainly arguable, but I believe 245mm is an ideal width for the Z’s fronts.

275mm is a great width for the rear (and, 285mm is less than ½” wider). The Z is a rear wheel drive car. The rear tires wear faster than the fronts. A front to rear stagger helps to maintain the best handling as the fronts wear faster (and lose more grip) than the rears.

You stated in your initial post that you like an obvious stagger. I say go for the 245 F/285 R. There’s no disadvantage except that 285’s are expensive. The driving experience will be great (not to mention the great look that you get from a staggered setup). The 285’s will not “overpower” the front 245’s. And, you can easily fit 285's with your rear wheels' offset.

--Spike

SparkleCityHop

iTrader: (30)

Your comments had me searching online while waiting for you response and I was reading about how the 350Z has some understeer built into it from the factory and that staggering the wheels further will increase the amount of understeer. I had no idea about this prior to your comments, so I am learning a lot today. (I didn't even understand what understeer really was until I looked it up on wikipedia. ME=NOOB)

I appreciate your detailed comments and information, as I mentioned, I'm just trying to learn and I have learned a lot from you and the others in this thread.

Since I am not planning on tracking or auto-x etc., I am going to give the 245/285 combination a try since I mostly just commute to work, etc. However, I live in the foothills of the mountains and if I'm not happy with the amount of understeer on my occassional mountain drive, I think that I might plan on purchasing an additional set of front wheels in either 9 or 10 before going to Zdays next year.

Thanks again to everyone!!!

Thermal1

iTrader: (23)

Just stopping in to share a site for calculations. It kindof combines all 3 sites you listed in your first post.

http://www.rims-n-tires.com/rt_specs.jsp

Spike100

^^ Excellent!

Thanks for the link.

Spike

SparkleCityHop

iTrader: (30)

That calculator is much better since it has everything in one calculator, thanks!

SparkleCityHop

iTrader: (30)

Thanks to everyone, I will be ordering some Hankook Ventus V12 evo tires tomorrow 245/35R19 for the front and 285/35R19 for the rear from TireRack. These tires had great reviews on C&D and on several forums and I just can't beat the price. For a married guy that has to get wife approval on everything, I'll never end up with Volks and Pirelli's

Woooohoooo!!! Thanks again everyone!

Thermal1

iTrader: (23)

If you remember, you should ask about a rebate. I seem to remember there is a $50 rebate available if you buy 4 hankooks. I think I saw the info on tires-easy.com when I was shopping a couple weeks ago.

Spike100

You are wise.

I’m old and can easily afford Volk’s and Pirelli's. But, I’m not sure I want very expensive wheels that might be damaged significantly by simply rubbing against a cement curb or costly tires that wear out in less than 30K miles.

It’s really only relative to what you can afford. There’s a great deal of freedom having stuff you don’t worry about and can replace easily and inexpensively.

--Spike

SparkleCityHop

iTrader: (30)

Thanks for reminding me about the rebate. I had seen something about that earlier, but had forgotten. I'll also check out tires-easy.com as well. Thanks for the info.

TRYNALIVEPRO

iTrader: (12)

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