I'm thinking about going for 17" wheels for my aftermarket set rather than 18". There are several reasons. Mostly, it's the lower cost and weight of wheel, and the lower cost and weight of the tires. With a 245/45 R17 tire, the diameters are nearly the same as the stock 225/45 R18 so my speedo will even be close.

That said, what are the disadvantages of going 17"? I know a taller sidewall can lead to more tire flex, but other than that, is there anything? Any issues with suspension and offset, like bump steer? Any issues with fitment? Anything else I've overlooked?

Thanks for your input, guys.

 

it wont be as harsh with 17's, but it won't look nearly as nice. But don't 18's give less body roll the 17 inch tires?

Don't know much about rims and tires...

 

If you dont care very much about appearance, then by all means go the 17 route. However, 18's really aren't that much more expensive than 17's, especially if wheels/tires are on sale. For example tirerack just had a closeout on Re01's for dirt cheap...

 

I'm rolling on a set of 17x9 +45 with a 255/40/17 Falken Azeni's and I love the setup. The ride seems alot better then the factory 18's and to me it just looks a lot better.

I'll try to get some pics up later,
Daniel

 

Here's a sample. Sorry for the horrible photography.

 

17" STI wheels.

 

17x9 with 255/40-17. One of the best advantages is the what it does to your gearing. Your artificial final drive with the 255/40-17 is equal to that of a 4.77 rear diff.

I don't think the wheels look small, they look just right.

 

Thats a sexy car.

 

I got some Mazda 3 17"s for my snow set up.

I'm wondering if I should keep the same size for the summer. The ride is more comfortable

 

Nice choice buddy, may i ask you whats the offset of your RPF1s?
coz i want to go for 17"s now...want to get 17x9 also...thinking if +35 ok or not

 

the ride is more comfortable because the tires are bigger. if you were to put 225/50/18 tires on your stockers, it would feel the same. conversely, if you were to put 225/40/17 on those mazda3 rims, it would feel the same as the stockers.

+1 for 17" rims. im going with 17x9s.

peppy, what are your rpms @ 60mph in 6th?

 

Tire weight is not really going to be a factor with 17's if you are trying to maximize traction. My 17's weigh 15.9lbs and my 18's are 17.4lbs. Both tires I have weigh the same at 26lbs. My 17" R comps ride better than my 18" street tires though thanks to the extra sidewall and 1.5lbs less weight of the wheel.

Philipchan - both my RPF1's are +45 offset. Stick with +45 if you want good fitment and no rubbing.

kersh4w - I want to say it's about 3250 or so @60. I've only put them on once so far and didn't really pay attention to the rpms. It doesn't add too much.

 

Peppy- Thx for the information, so the 17x9 +35 offset will rub...? i'm looking for a set of cheap 17x9 rims for track use....(not too heavy ones) you have any idea?
I was looking at this one
http://losangeles.craigslist.org/lac...089924164.html
only 450 a set of 17x9....
want to put the 255/40/17 Federal595RS-R on them

 

I'm not saying the +35 will rub, but I am saying with the +45 you can be sure they fit with any width tire and no modifications to your wheel wells. A week or so back you could have gotten the some 17x9 +45's from discount tire for less than$200. They weighed 20lbs which isn't bad. I just checked now, but they are all gone.

 

please excuse my ignorance, but does that translate into greater acceleration and or top end speed? We met at Mazcare and I remember you talking about the wheels, but I never understood the benefits

 

Peppy- hmmn...coz i already banded my RPF1s on the track...it's a pain to fix them, thats why i want to buy some cheap ones for track use only, looking for used or new ones...but RPF1 still my best taste for weight and price ^^
ATL-GP- I think the benefits are better acceleration, the rpm will go up a bit faster than the 18's, but you will loss some of the top speed, sth like it was 150mph max. now may be only 140mph, but on the track, you dont need that much of top speed, the acceleration is more important,
second is the weight, the 17's with tires is lighter than the 18's with tires, the wheels weight is like 4~10 times of the body weight, if you save 8 pounds total on wheels, its the same as saving like 30~80 pounds of the curb weight.
the last thing is tire saving...17's tires is much cheaper than 18's, if you do track your car...you need to buy tires like every couple months ^^
Please correct me if I said sth wrong

 

hmmmmmmmmmmm...reallllly, that's interesting to know..Thanks

 

Anyone know if 40mm offset will totally avoid rubbing on 17 x 8.5's? I found a killer deal on some lightly used rpf1's and want to make sure I can just throw 'em on

 

Back to math class for you... you are effectively running with a 4.56 diff with your set up, not 4.77. You would need to have a 24 inch diameter to be at 4.77 and you are only at 25.2 inches.

 

Thank you for correcting me rx8thunder. I just guestimated based off formulas I found on sites meant for off road trucks. I could never find an accurate way to calculate it. I would very much appreciate it if you could post the formula you used to get those numbers.

 

Here's the math...
Divide 4.77 over 4.44 = 1.079166667
Divide OEM wheel diameter (25.9 inches) by above factor = 24 inches
So, net result is you need a diameter of 24 inches to match the effect of a 4.77 diff

Your wheel diameter is 25.2 inches producing a factor of 1.027777778 or 4.563333333 in gear ratio terms

 

Please correct me if i'm wrong

4.77 over 4.44 = 1.079166667------correct

OEM wheel diameter is not 25.9,
stock tire=225/45/18,
(225mm/25)=9"inch,
9"x.45=4.05"(how thick is your tire)
4.05*2=8.1"
8.1"+18"=26.1"(OEM wheel diameter)

So stock 4.44 gear=26.1"wheel diameter,
if u wanna get 4.77gear,
its gonna be 26.1"/4.77x4.44= 24.3"(wheel diameter in order to get 4.77gear)

if u are getting 17" rims,
255/40/17
255mm/25=10.2"
10.2"x0.4=4.08"
4.08"x2=8.16"
8.16"+17=25.16
26.1"/25.16"x4.44=4.61
(so by my result, if you are using 255/40/17, you are getting 4.61 gear)

but what size of tire will get 4.77 gear?check the information below↓
let say 255/35/17
255mm/25=10.2"
10.2"x0.35=3.57"
3.57"x2=7.14"
7.14"+17=24.14"
YEAH...24.14"is < than 24.3"
So if you get 255/35/17, then you are getting higher than 4.77 gear !!!!

 

Calculations seem correct based on 26.1 diameter but where did you get that stat from? Most every tire I have seen within Tirerack that is OEM size has a diameter of 25.9 inches - for example.

 

base on my Calculations, it should be like what I typed on top...
but it's strange...
on your site,
225/45/18=25.9"
255/40/17=25"

may be that 45%of the 255mm is not exactly 45% then
(but 1 more thing, for example, the brand new tire is 26.1, but after driving a while, your tire is gonna lose, may be thats how they got the number to 15.9 ???, just guessing)

 

coz 225/45/18
225 is how wide is your tire (by mm)
45 is how thick is you tire, it means 45% of how wide of the tire,
so 225x45%=101.25mm
101.25mm/25=4.05" how thick it is...
18" wheels +4.05"+4.05" =26.1"
( because rubber on top and the bottom part, add together to get the whole diameter)