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17x8 Rims... Tires Size?

22K views 18 replies 5 participants last post by  titter 
#1 ·
so im going to need new wheels and tires to put the power down from the new motor.

tire information on the internet is a headache. thousands of threads and arguments to sift through. so i figure i would ask people i know what they think. i have it down to 2 sizes that i know are the best for my wrx wagon.

im going 17x8 +46-48. do i want 225/45 or 235/40. tell me which, and tell me why.

please, no debates on tire brands, or what effects they'll have on the speedo and whatnot. im just having trouble making a final decision. performance drag racing daily driver oriented.
 
#2 ·
Rim & Tire Size Calculator. Custom Offsets - Wheel-Size.com

I will share with you a site (with your specifics entered) that has been known to keep me occupied for hours on end.

Based on the information that the site gives, and my limited first hand experience of drag racing, would it be wrong to say that the extra sidewall height offered by the 225/45 tire(s) (over the 235/40) may be of a benefit when adjusting tire pressures (down) to achieve an effective launch? Other variables aside, the 225/45 tires theoretically offer a slightly higher final (effective) gear ratio. However, maybe a slightly lower final (effective) gear ratio is better suited for the characteristics of your car...

I don't know if the principles that apply to (the tires of) top fuel dragsters, funny cars, etc. are useful when it comes to an AWD street car on the strip, but hopefully I have been of some help to you!

I look forward to the responses of our other members.
 
#3 ·
yea the lower sidewall will change my final gear for more acceleration which i guess i want for drags. but im also thinking daily driving safety. i dont want to get all squirly at low speeds.

thanks for that link! :) that site is unreal!!
 
#5 ·
I'm with Mosc, 235/40 is a good place to be and there are a wide variety of race specific tires available in that size . Your building a track car so you really don't need the fender linings that tend to get in the way of wider tires. Im not usually one for rolled and pulled fenders but if you can fit wider rubber the wider contact patch should give you a bit of extra grip on the starting line.
 
#6 · (Edited)
im already converted to sedan width, and extra castor front C-arms. so im not worried about rubbing while turning. and i dont mind rolling my fenders so i wont rub on the outside. i dont want to have to pull them though. im also on JDM STI suspension so im lowered about 20mm

and its a drag car, not track ;) so i dont need to worry about lateral G's.

thats the reason i want to fit x8 width and not x7.5 width. but if the extra 10mm of tire is going to complicate things being a wagon, i might stay 225/45 which is oem sizing and see how it goes. then maybe the next set of tires go 235/40


appreciate the info!
 
#8 ·
I've heard of people having to roll fenders on a wagon for 225/45R17 on 17x8 +48. Still, if you're willing to do it you will love the gearing advantage 235/40R17 brings (though not sure how much you need that on the auto). If you get some 11-14 WRX take-offs, they'll be much higher offset and you can probably get away with 235/40R17. It's a thought.

The concern with clearance is purely in the rear.
 
#9 ·
thanks mosc :) the wheels i get will be from jdmracingmotors. going to make the trip once my motors swapped and pick from the dozens of sets they have.

i already had a feeling i would have to roll my fenders with 17x8. my original plan was 17x7.5 sti bbs rims. but those oem bbs in 5x100 are rare and expensive. also i need to put the power down to the road if im gonna make good e/t's

would my extra camber in the rear help fitment at all? i forget the exact # but im a few degerees over stock.

i would like a lower gearing. my 16's are already on a lower sidewall. it really helps the 4EAT 60ft times, and helps keep my speedo gauge low to avoid tickets lol

i think i might just say eff it and do what it takes to fit 235/40's.
 
#10 ·
negative camber helps fender clearance yes. The tire is 25" top to bottom or 12.5" from the middle and you're talking a 2 degree camber (fairly extreme for a street car already) I'd guess so that's a trig problem resulting in Sin(2 deg) * 12.5" = 1/3" more clearance.

If money's tight not sure what jdmracingmotors has to offer that beats some used 11-14 WRX wheels but hey, gotta look good too right?
 
#11 ·
yea thats definitely an option, but i wanted a lighter wheel than those ones. 22lbs i think they are? i can save weight and money getting wheels from JDMRM. and i might even get lucky that i get some rims with decent rubber on them that i can burn down the strip before i buy new tires. not to say "price no concern" but im not gonna scrimp in the wheel dept. i dont mind spending more $$$ when i know its worth it. i think the 11-14 rims look pretty good but looks are last on my list. if a set fell in my lap for a good price and saved me a 2h trip i would totally take em.

also a plus from going to JDMRM is i can bundle with a brake package and save money on both. im going to need 4/2 pots to help me stop. dont think the H6 upgrade will cut it. and brembos arent really worth it.
 
#12 ·
the more i stare at the 11-14 wrx rims, the more i see them on my car. i guess 22lbs isnt too bad for a non forged 17x8 rim. they're really plain looking which is what im going for.

because: sleeper wagon!
 
#13 ·
I'm only stressing it because of how painfully tight the rear wagon fenders are on the 02-07 WRX and how hard it is to find aftermarket wheels with Subaru's offset. The 11-14 WRX wheels aren't super heavy. They're lighter than the 1" narrower wheels Subaru had been putting on the WRX the previous 5 years. The forged BBS 17x8" on the 05-07 STi were a little lighter at 19 lbs but that's a very high dollar wheel. 22 isn't what I'd call a heavy wheel for 17x8".

235 at +53 is also getting close to the rear strut. On my 04 STi I ran 255 at +48 with ~1 degree negative camber and it cleared the strut by a fraction (IMHO the ideal strut clearance). Pretty sure you're looking at similar clearance back there to what I had. Compared to my setup there you'd be 10mm further from the strut from the tire, 5mm closer from the offset, and 5mm closer from camber (I'm assuming you're at -2 degrees). The tire's a little shorter than the one I was using which will help both fender and strut clearance. Might be limiting your camber a bit with this choice if you intend something really extreme but I don't think so. -2 is not going to give remotely even tire wear on a freeway, that's for sure.

I'm not going to tell you I've done it and it'll be completely painless but my math says you should be able to throw 235/40R17 on 17x8" +53 wheels with stock GD wagon fenders clearing by a fraction on both fender and strut and virtually any other offset is going to be much more work. Don't sue me if I'm wrong!
 
#14 ·
i wonder if i could find some weird 50 or 51 offset in the pile at JDMRM.

i called them and they said we can confirm fitment on any pair before i leave the store. :)

appreciate your info man. good stuff as always. not going any lower than +48 for sure.
 
#15 · (Edited)
@mosc so i got free set of Rota SDR's. they came with 225/55/17 (no clue why that tire size is on there) with decent tread so i would like to use them if i can. i know my speedo will be way off and so will my gearing. will that add too much stress to my drivetrain?

you think they would fit? or should i not even bother trying and just go buy new tires.

and i cant just slap them on and see as my car is still having the motor swapped. need to have these wheels ready when i go pick up the car.
 
#19 · (Edited)



17x7.5 +48 Rota SDR
225/45R17 Goodyear Eagle Sport

they fit no modification. its only been 100km but had some bumpy and winding roads and no rubbing.
looking at this up close, going 17x8 and 235/40 probably would not have fit.

thanks @mosc for the help and answering my pm's :)

i think i need mudflaps now lol. more for safety than style.
 
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