Tire and Wheel size guides

[MattR]

Yes they are taller, quite a bit taller. I originally bought these wheels with a set of 225's on them, and they looked way stretched. So on a 7.5 with 235's, that should look great

[MattR]

Here are the 8" wheels with 225's.

[100_Percent_Juice]

Is there a benefit to going bigger? I always thought it was best to stay stock size if everything else is stock?

[cody]

Going with a wider tire means more contact patch which improves stopping and latteral grip, but if you too wide for a given rim, the handeling get's mushy from the sidewall rolling over and grip can actually be worse. I agree with Matt. In most cases 235 on a 7.5" rim would be ideal (as long as it doesn't rub). Some 245 wide tires might offer more grip, but possibly at the cost of spongy handleing and you wouldn't like the way it looks.

[sperry]

Originally Posted by 100_Percent_Juice

Is there a benefit to going bigger? I always thought it was best to stay stock size if everything else is stock?

Bigger tends to mean more traction, which means better braking, higher lateral G's, better acceleration (if you were traction limited to begin with). But it also means, more tramlining, more noise, worse mileage, and worse acceleration (if they're heavier and you weren't traction limited to begin with).

Really, the process to pick wheels/tires for performance is to do this, and I'll include my own answers for my TT car:

Q: What width tires will meet my performance goals?
A: As wide as friggen possible that will fit under the car w/o a widebody kit

Q: What type of tire will meet my performance goals?
A: R-Compound DOT legal race tire

Q: What diameter tire do I need?
A: As small as possible while clearing StopTech Brakes, i.e. 17"

Q: What tire meets the above criteria?
A: Michelin Pilot Sport Cup, 255/40/17

Q: What size wheel is ideal for the selected tire?
A: 17"x9"

Q: What offset is necessary for the ideal wheel to fit?
A: +43 to +48

Q: What wheel fits the above criteria and matches the PCD of the car?
A: 5zigen FN01RC, 17"x9" +43 5x114.3

Granted, I've done a lot of other work to open up my possibilities, like converting to the '05 STi hubs, rolling my fenders, cutting fender liners, going to coilovers, etc. Most people can't start out looking for 255's... 245 is usually pushing it... but the process is the same.

For you, you're probably looking more along the lines of this:

Q: What width tires will meet my performance goals?
A: Something that will increase handling performance w/o drastic fuel economy or comfort sacrifices, probably a 225 or 235.

Q: What type of tire will meet my performance goals?
A: High-Performance All Seasons

Q: What diameter tire do I need?
A: 18" for decent bling factor w/o clearance issues

Q: What tire meets the above criteria?
A: Falken Ziex 512, 225/40/18 or 235/40/18 (both are very close to OEM overall size, 225's are a little short, 235's are a little tall, but both are fine)

Q: What size wheel is ideal for the selected tire?
A: 18"x7.5" for 225's, 18"x8" for 235's

Q: What offset is necessary for the ideal wheel to fit?
A: +48 to +53 for 7.5" wide, +45 to +50 for 8" wide

Q: What wheel fits the above criteria and matches the PCD of the car?
A: I'd go with any 18"x8" +48, or 18"x7.5" +48 in 5x100, the lighter the better

[cody]

Scott's post FTW.

Oh yah, on my most recent trip to Sonoma County last weekend, I had the RT-615's in 225 width (which is actually as wide as most 235 width tires) on and my gas milage was 25mpg instead of the 27-28 I'm used to seeing with my 225 width Proxes 4's.

[100_Percent_Juice]

Thanks for taking the time out for that post scott, it really helped.

Originally Posted by cody

Going with a wider tire means more contact patch which improves stopping and latteral grip, but if you too wide for a given rim, the handeling get's mushy from the sidewall rolling over and grip can actually be worse. I agree with Matt. In most cases 235 on a 7.5" rim would be ideal (as long as it doesn't rub). Some 245 wide tires might offer more grip, but possibly at the cost of spongy handleing and you wouldn't like the way it looks.

When I asked earlier "Is there a benefit to going bigger?" I wasnt really refering to width as I was to Height. I asked that after matt said his wheels/tires were taller then stock. I just know that from when I had my truck(which I know is way more of a size difference then we are talking about here) and put bigger tires on it, the noise went up, gas mileage went down, and braking ability went down. Does Scotts below statement about wider also apply to taller tires?

Originally Posted by sperry

Bigger tends to mean more traction, which means better braking, higher lateral G's, better acceleration (if you were traction limited to begin with). But it also means, more tramlining, more noise, worse mileage, and worse acceleration (if they're heavier and you weren't traction limited to begin with).

[sperry]

Taller tires change the effective final gear ratio between the engine and the road. Bigger tires will mean more rotating mass which effects you as described on your truck ('cept for the noise perhaps). It will also make your speedo read low.

Shorter tires will help your acceleration, and your fuel mileage because the freeway rpms will be higher. Also your speedo will read high.

In general, I'd try to match the stock size in outside diameter, just for speedo accuracy alone. Or lean towards the short side.

[Joeyy]

235/40/17 picture for you on a 7.5 wheel.

[Kevin M]

235/40R17s on 17x8.5

[100_Percent_Juice]

Thanks for all the pics^ those look nice.

[ryan4601]

scott or matt can probably chime in with experience on this one. Im looking to get some summer only rubber for my car. im looking at 245/40/18 on a 18x8 rim +48mm offset. will i have rubbing issues with this? my car isnt lowered all that much, and it dosnt seem like im really close to rubbing with the 235/40/18 all seasons im on now. thanks for the help.
ryan

by the way im deciding between:
Bridgestone potenza RE050A PP (tread life will be an issue)
Falken Azenis RT 615
Never tried the Falkens before but it seems everyone on here has, i have the RE050APP's on my s2000 and they pretty much rock on that car. decisions decisions.

[cody]

The 615's are an amazing bang for the buck but they tramline like a mofo. I don't know, maybe all wide sticky tires will do the same thing. They run wide too so getting them in the same size as the all seasons you're running would be like getting them in 245 width.

[Kevin M]

245/40R18 is awfully tall for a WRX. I'd stick to 235/40s personally.

[k-dogg39]

What about 225/45/17 Azenis on a 17 X 7.5 +48 on a wagon? Would there be too much rub?

[Kevin M]

Shouldn't rub much, if at all.

[k-dogg39]

Originally Posted by BAN SUVS

Shouldn't rub much, if at all.

Didn't think so really, but wanted to get some opinions. The only other suspenstion mods I have are STI Pink wagon springs. Thanks!

[Dean]

Originally Posted by k-dogg39

Didn't think so really, but wanted to get some opinions. The only other suspenstion mods I have are STI Pink wagon springs. Thanks!

Those may well cause a bit of rub with the 615s in the rear.

Pull the rubber strip off and maybe a little roll of the lip.

Cody???

I think he has/had rub with 225s, lowering springs, and 48 offset.

[Kevin M]

Cody's 615s didn't rub this weekend. He pulled the rubber strip off but there's no roll to his fenders.

Anything that doesn't rub stock won't rub with different springs on the car.

[Dean]

Cody had rub. Not sure what he has done to alleviate it. I defer to him.

[cody]

Running exactly what K-Dogg is asking about (225/45/17 Azenis on a 17 X 7.5 +48 on a wagon), I did have rub, even with -2.2* of camber and the rubber strip removed. Now I have only -2* of camber in the rear and they don't rub at all. The only difference is that replacing the Eibach's with Crucial Racing Springs has raised the rear a touch and they have higher spring rates.

If bugeye and peanut eye wagons have the same clearance in the rear, I think K-Dogg will be fine since we basically have the same rear springs, but he might need to get a similar alignment to mine. If anything, I think peanut eyes may be able to fit slightly wider tires.

http://www.crucialracing.com/products/springs.php

These are the same high performance spring rates as the highly-lauded and thoroughly-tested JDM STi "Pinks," but the Crucial springs have better materials quality, smoother progressive rates (plus are progressive both front and rear, while the JDM Pinks are only progressive on the rear, and linear front), offer slightly more drop up front for a nicer, more even stance (JDM Pinks are 1.0" both front and rear on WRX, 10mm front/rear on STi)...

[Kevin M]

wtf m8? You told me this weekend you didn't rub at all.

[cody]

I told you that I didn't have rub at all since installing the new springs...

[Dean]

Toldja! That is why I lightly rolled Sue's while I had the tool.

[k-dogg39]

Thanks guys! I might be able to get these for pretty cheap, so wanted to check if it would be worth it.