Wheel & Tires Basics

Discussion in 'Modifications & DIY how-to' started by jt money, Mar 8, 2006.

  1. jt money

    jt money 350hp mmm mmm Good! Supporting Member

    Wheel & Tires
    Adding Significant Levels of Grip

    One of the most popular upgrades, wheels can enhance the look and/or performance of your ride.

    Acceleration, handling, and braking can all be affected by the weight of the wheel. Just motoring around town, you may not notice differences in wheel weight. However, since this site is biased toward performance tuning, wheel weight can play a huge role factor. It is a matter of simple physics.

    First, lets talk about un-sprung weight. Un-sprung weight is defined by as weight that is not sprung…which means anything that does not ride on (supported by) the suspension (read wheels, tires, brakes, and axles). Since the wheels/tires rotate and are what transfer circular motion in to forward motion, their weight has the largest impact of un-sprung weight.

    It is easier to understand if you think about it in terms of a bicycle wheel/tire. If you have a small and a large bike turned upside down (so you can spin the front wheel with your hand), it takes more energy to get the larger/heavier wheel/tire moving than the small, light wheel. Also, once the wheel is spinning, the larger/heavier wheel has more momentum (mass x velocity) than the smaller and is more difficult to turn. Along those lines, it also takes more force to stop the heavier wheel.

    In a nutshell, heavier wheels can negatively impact acceleration, braking, and handling.

    Now there is the argument that slightly heavier wheels have no noticeable effect. Manufacturers try to strike a balance between light weight, durability, cost, and style (good looks).

    Scooby Poop (bottom line): Buy the lightest, strongest wheels that you like and can afford.



    Stick to it Baby!
    The WRX is a great car in stock form. However, from the factory, the WRX is a capable handler...but not exceptional...on dry pavement.

    To turn your WRX into the serious sport car that is, the single most dramatic thing you can and should do is change the OEM Bridgestone RE92 mud and snow tires to a tire that actually grips the road.

    With the RE92, the WRX can be slid around with relative ease. However, once you put some decent, sticky tires the WRX transforms into a whole new beast.

    With the high performance tires, turn-in, steering feedback, and lateral grip is phenomenal! By switching to "ultra-performance" BF Goodrich KDW's (see tirerack's category descriptions…one step below "max-performance" and a few steps below "R" rated tires) lateral grip increased by .04-.08 g's depending on the corner. This translates into 5-10 mph faster through the corners (low to medium speed corners).

    Get the best/stickiest tires you could afford. If you want to stay with true "street" tires, Bridgestone S-03's, Michelin Pilot, Pirelli P-Zeros, BF Goodrich KD, and a few others will provide maximum performance. My personal preference is the Bridgestone S-03's...Great tread life (relatively speaking), quiet (relatively speaking), and pehaps the stickiest out there in standard street attire. The most economical choice is the Kumho Ecsta MX...great tire for the money.

    If you live in a dry climate you may be able to get away with "R" compound tires (Racing compound…most R compound tires do NOT have the ability to dispense very much rain/water and therefore hydroplane with relative ease). Also, R compound tires typically only last at most 10,000 miles.

    There are a few drawbacks that should be noted with high performance street tires. Though the WRX is not known for its quietness…the tire/road noise is much more audible. Also, stiffer sidewalls make the ride harsher…and the some tires will have a tendency to "tramline" (follow seams/cracks in the road).

    *thanks to Scoobytuner for the artical.
  2. On my 05 WRX, how wide can I go with 18s without having to widebody it. I havent really been able to find anything on the web or here about it. Just by measuring, which is purely guessing, I think I could fit 245s under it, but im not sure. I dont want it to be bull frogged, but I would like max grip, wide always looks really good too, to me.
  3. blindfold

    blindfold Active Member

    SCCA link
    ADVAN Neova AD07----------------Potenza RE-01R-----------------Dunlop Direzza Sport Z1

    More Details
  4. Good stuff to know, do you thing 245 is to big to run on my car? And if i go that big, will I have to mess around with my offset?
  5. pEd

    pEd This ain't no Piccadilly!

    245's will be fine on your car as long as you've got an 8" wide wheel to put them on.

    You may have some rubbing issues, depends on your suspension setup and what you do with the car.
  6. clemsonscooby

    clemsonscooby Active Member

    Most rubbing issues with a 245 come from the rear fenders. I know the 02/03 cars depending on the alignment and actually tire width you may have to shave a little out of the fender. I ran a Hoosier 245 R, that is much wider than most 245's. I was also running almost zero negative camber in the rear which pushed the top of the wheels close to the lip of the outside of the fender. I used an angle grinder to take off enough metal and touched it up with some paint to prevent corrosion. A 235 for daily driving is plenty fine though. A 245 is only going to cause more drag and suck up gas.
  7. Awesome, yeah this will be a daily driver. I just know the 205/50's i have on there now have to go, way to squishy. they like to squeal into sharp turns. thanks for the info, much help. Think I will stick with the 235's
  8. Matt

    Matt Think before you post Staff Member Supporting Member

    hell even 225 series would be sufficient. :)
  9. FACE

    FACE Active Member

    I love my RE01Rs

  10. salimjim

    salimjim Member

    so i was looking into different types of tires and i was wondering if max load weight has to do anything with sidewall rigidity. i want some tires with a stiff sidewall and want to know how to compare tires in that sense without having to drive on them. thanks
  11. Alex

    Alex Community Founder Staff Member

    I do not believe the correlation is high enough in our application for it to really matter. If you want a stiff sidewall, simply look for tires that are note that or research tires that are well known to have stiff sidewalls, like the OEM RE070s.
  12. nik_05STi

    nik_05STi Member

    Whoever was asking about running 255's, i run 255 on my stock BBS rims. I was told they would throw the odometer off and affect quality but i havent noticed a difference. Dont let the tire "pros" (firestone, kaufman, goodyear, etc..) tell you what to run. Do what you feel like doing. I plan on running 255's from now on. Next set of tire will probably be Direzza, BFG T/A, or Bridgestones.
  13. bixs

    bixs Supporting Member

    Odometer will be thrown off due to the sidewall ratio, e.g. 245/40/18 isn't the same sidewall height as 255/40/18.

    it's tiny. I did the math for my 235/40/18's and it was something like 25300 miles on odometer if I do 25000 miles....so really tiny.
  14. Matt

    Matt Think before you post Staff Member Supporting Member

  15. bixs

    bixs Supporting Member

    forget pi?
  16. Matt

    Matt Think before you post Staff Member Supporting Member


  17. WRboXer

    WRboXer Active Member

    Since this is the tire thread, i am going to discuss proper sizing.

    Running the biggest tire your fenders can fit is the incorrect method of choosing a tire width. The width of tire you should be running for a true street car that sees performance driving should be directly correlated to the size of the wheel you are running.

    I would personally consider ballooning a tire onto a wheel easily worse then stretching a tire on to a wheel.

    Both are not ideal situations, but ballooning is easily the worse of the two. It creates less steering feedback, you have to run higher pressures to maintain a decent sidewall profile and even then has the worst sidewall profile possible(aka the sidewall has started to create an acute angle that will multiply with load), further the higher pressures necessary will make the tire run hotter be more greasy and wear out faster. Essentially, you just spent more money a bigger tire that in most situations performs worse then a properly sized smaller tire.

    Note I said "in most situations". A bigger ballooned tire should and will actually ride nicer. Taller sidewall and less square profile means the tire has more give. Because that tire has more give/smush/squat, it should also brake better not only because of a bigger contact patch but more so because its "smushing" more. Further if you a drag racer should help out with traction for your 60'. In other words i am saying that you are creating not just a wider contact patch but also longer contact patch due to more give in the sidewall. Also if you are looking for some longer gearing going with a bigger tire is a sure fire way to get it.

    To sum up, ballooning the biggest tire you can fit onto a small rim is not bad per say , just know that if it came to an auto-x, track day, or any other handling event, you most likely have an inferior tire setup compared to the person next to you with the same sized wheel but properly sized tire.
    Last edited: Apr 26, 2011
  18. Superdude

    Superdude Active Member

    I'm looking for info on tire/wheels for auto-xing. I need to run a 245 next year. 245 is the max width for the STX class.

    1. Can i get a 245 on a 05 STi wheel? Is it safe for racing?
    2. How much issue will there be in with fitting that wide of a wheel/tire in the '05s fenders?
    3. I'm pretty sure that's too large to fit the 05 STi wheel, what's the ideal size to run?
    4. Going up to a 17" is going to hurt me coming out of the tight turns, is there a 16" wheel/tire combo with a width of 245?

    The current aliegnment is roughly this, going on memory here:
    front: -2.3 cambor +.2 tow rear: -1.85? cam -.2 toe

    Any info's good info.
  19. Matt

    Matt Think before you post Staff Member Supporting Member

    I've seen 255+ series tires on 02 WRX wheels...it all depends on the tire.
  20. Superdude

    Superdude Active Member

    i've read/heard 225 is the max for the stockers. 02-05 i have 225 RE-11s on 05 wheels, and it's bulging over the side pretty far. even the 225 Dunlops hang pretty far off the rim on the 02 wheels i have. at least it makes it pretty hard to get curb rash.

    i'm looking for a light-weight wheel/tire combo to auto-cross on. i like to run 39psi in the front and 40psi in the rear. helps the car rotate quicker.
  21. nik_05STi

    nik_05STi Member

    Im running 245 on my sti wheel with no rubbing. Even though its wider than the recommended 225 size, i wouldn't say it handles any better.
  22. dpulse2930

    dpulse2930 Member

    Anyone have any idea on color code for 2011 wrx wheels? One of my center cap chipped by the subaru logo and was hoping there is touch up paint close to oem wheel color?
  23. ssen

    ssen New Member

    Opinions on tire change

    Hey guys,

    A little concerned and thought I'd ask on here:

    So I got my stock Dunlop tires on my 2013 WRX changed (which i believe were 235/45/R17) out to 245/40 /R17 Yokohama. I have the OEM 17x8 WRX wheels.

    Changing it to the Yokohama's with slightly wider tires - will this impact driving in terms of the tires wearing out quicker? or perhaps brushing the fender liner(which I have not confirmed yet).

    Thoughts? Opinions?

    Last edited: Mar 1, 2015
  24. scoobaru

    scoobaru Active Member

    You'll be fine. They are a slightly smaller sidewall so they will have more revolutions per mile, but I wouldn't worry about them wearing out quicker. The GR can handle a decent sized tire without rubbing.

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