Zoomspeed

My FD is lowered 1.25" using the H&R springs, and I got a set of those 18x9 wheels for sale. I was going get 225/40/18 tires for the front to try to avoid any wheel rubbing, but the local wheel shop said that a 225/40/18 is to narrow for a 9" wide rim, and with that size the wheel would stick out further then the tires.

Is any one running 225s on a 9" wheel? What size do you guys recommend? I'd rather not roll my fender lips.

Thanks for any help.

ThirdGenRX7

245 that would be fine I think

Zoomspeed

Is that from experience?
Does anyone have any other comments or suggestions for me?

Mach2

It also depends on what Brand and model tire you get. Some tires allow a wider rim and others less so. I think that a 225 on a 9" rim is on the "high" side, but should work perfectly. I agree on the rolling fender lip issue(rather not). From what Dan(Dclin) said in his post I think a 245 would rub so you don't want that. A 225 or 235 should work fine though! Btw did you receive your new wheels yet? How do they look in person? Would you recommend them to others?

HedgeHog

Racing Hart Type C2, 18x8.5, 42mm offset, Bridgestone S-02 Pole Position, 245/40-18.....rubs badly. Rolled fenders and raised coil-over by 3/4" to clear. Running 1.6 deg negative camber. Looks great though. ...

Mach2

Hedgehog,
Have any pics of your setup?

Zoomspeed

yup, I got them on monday. They look great in person. The pictures don't do them justice. I can't wait until I get them on.

AARotary

I got this setup in the front it rubs in the beginning but I did some mods to the inner fenders and it works fine for for. I think that 18x9 on 225 is a bit wide I would recommend you to get 235 or 245 should do it. 235 and 19x9 on my set up, the wheels stick out a bit. I think I am going to 245 in the front later on.

HedgeHog

Not very clear pix but here goes:

Zoomspeed

I thought a 225 is more narrow then 235 and 245. Am I wrong?

dclin

iTrader: (4)

Hi all,

Here are specs for Pirelli P-Zeros. If you look at 225/40/18s, the manufacturer's approved rim width range is 7.5in to 9in. Pretty much any desirable tire in that size lists 9in as an approved rim width.

http://www.tirerack.com/tires/Spec.j...em+Asimmetrico

Tirerack has specs to pretty much any tire you will want.

I am recommending 225/35/18s, 225/40/18s, and 235/35/18s for the front. I am making these recommendations because :

1. I am playing it safe, as that I want everyone of my buyers to be happy with their purchase, and I do not want people to experince anything negative.

2. There are factors regarding fit that I have no control over - camber settings, how much lowered, and tire manufacturer (different tires will vary in size and profile, manufacturer to manufacturer - for the same rated size)

Food for thought - I have 255/35/18s on the front, stock front suspension, and I love it. I'm not recommending it though. Why? Because of the above two points.

Max Copper just put 285/30/18s on 18X10 (+50??) rims. Valspeed has 255/35/18s on 18X9 +45 on the front. Steve Cirian has 265/35/18s on 18X10 +50. Taz has 17X9 +40 with 245/??/17s. M2s website RX7 (the black one) has 18X10s (offset ??) with 285/30/18s. They say it fits great. I forgot to ask how much it was lowered, but it looks like at least 1in. FYI, 285/30/18s = 24.73in diameter.

My biggest concern is the overall diameter of the tire/wheel combo. Sorry, I don't think I made that clear in my Wheel Buy post. I've think I've established that you can put widerubber underneath, given the correct offset of the wheel.

Here is the diameter breakdown:

225/50/16 = 24.86in ( stock)
225/40/18 = 25.09in
225/35/18 = 24.02in
235/35/18 = 24.48in

Taking 19in wheels as an exercise, if you put 245/35/19s on, the overall diameter of the tire/wheel combo would be 25.75 in- almost a full inch taller then stock (.89in to be exact). So, if you install that combo and lower it 1in, the tread of your tires will be closer to the inside top of the fender by 1.445in (.445in + 1in, almost a full inch and a 1/2. (225/35/19 = 25.02in dia might be a better choice)

Probably not a too much of a problem when bottoming out with teh wheels pointed straight, but people start having problems when they are turning the steering wheel and hitting an incline driveway (therefore compressing the suspension)

When the wheel is turned at an angle, the thread of the tire no longer has the luxury of tucking into the wheel well, but will now come in contact with the fender lip if the suspension is compressed too much (meaning hitting that drive going to fast). This phenominon has nothing to do with the width of the tire , and little to do with the offset or width of the wheel. It has to do with the relative distance between the top of the thread and the fender lip (looking form birds eye view, down onto the tire thread.

The only solution to this is not lower it as much, or use a smaller diameter tire to compensate for this. Also, when you enter inclined driveways, enter it at a sane speed,hehe, and/or straighten your wheel.

Thus, when I recommended the sizes above, I was looking more at the diameter. I'm not really worried as much about the width. Stay shorter then stock, and you should be ok.

When someone buys larger diameter wheels (like 18s and 19s) they often make the mistake of buying tires that do not compensate (enough) for the larger diameter (by having shorter sidewalls). It's a common misconception that running a larger wheel means you will have a larger overall diameter of the wheel/tire combo. If you pick the right sizes, you can have (near)stock diameters or smaller.

Zoomspeed, I would recommend 225/35/18s (24.02in dia) as that you have lowered the front that much. That is my recommendation, but you are more then welcome to experiment. You might also look into Pirelli PZero Assym 255/30/18s (24.02in dia).

Hope that clarifies things!

dclin

iTrader: (4)

Here is an example of how tire specs differ. In this case we are comparing specs for the same rated tire size (285/30/18s) of not only teh same manufacturer, but the SAME MODEL!

The difference is probably because these are OEM tires, and Porsche needed tires with different specifications. Keep in mind that Pirelli also has their P-Zero Rosso availalble in 285/30/18s, though specs were not available for that. I'm betting it's different then the two below.

Pirelli P-Zero Assim specs:

285/30ZR18 102Y SL N2 (Porsche OE) 140 A A
Recommended wheel width: 11-13" Measured wheel width: 12" Sectional width:13.6" Diameter: 26.1"

285/30ZR18 93 SL N3 (Porsche OE) 140 A A
Recommended wheel width: 9-11" Measured wheel width: 10"
Sectional width: 11.1" Diameter: 24.9"

The recommended wheel width is what wheel widths you can mount these tires to. Measured wheel width is the wheel width used to design the tire to the rated specs.

If you were to mount the tires to differnt wheel widths then what is listed as 'Measured wheel width' (within recommended wheel width range of course), the specs will change again.

If you are a nerd like me and have time to comb thru all the specs of different brands and models, you will see that this is not unusual.

Do you guys see why I am recommending the smallest approved tire sizes for my wheels? I am in a situation were I want my buyers to be happy, but I have no control over alot of factors. :p