What would the FIST feel like with higher profile wheels/tires?

Discussion in 'Fiesta ST Wheel and Tire Upgrades' started by Mike, Oct 14, 2013.

  1. Mike

    Mike Member

    The rides on the 17"s feel fine in normal roads but can be a bit jarring in cement or uneven roads. For everyday driving I'm curious how the car would feel on the tires/wheels that can take a little edge off. What would be the trade off? Is it worth keeping two sets of tires, the 17"s for fun and 16" for my ass?
  2. Register or Sign in

    Advertisement Sponsor

  3. Removed

    Removed Guest

    I'm downsizing to 16" wheels for winter tires. I'll let you know.
  4. Mayhem

    Mayhem Active Member

    I'm more curious about the handling rather than the ride.

    I'll be going with two dedicated sets of wheels/tires... but contemplating between 15"/16" steelies for winter? and... between 16"/17" for my regular set.

    Probably having my winter set installed when I pickup the car... so I don't think I'll be using the stock wheels whatsoever. My first ride will probably be on the steelies.

    I really prefer the look of more tire.. Not a fan of the whole rubber band thing... But I'm wondering how much of a difference there will be in handling/control. It is only a 1" difference... Which isn't massive, but still makes a diff.

    Of course the smaller wheels/fatter tires are going to give more cushion. And probably be cheaper. But.... at how much of a cost in performance?

    Would like to see more thorough feedback in that regard.
  5. Removed

    Removed Guest

    It only snows sporadically here, so I went with 16" 'Performance Snow" tires that are supposed to handle better in dry conditions. I'm hoping that I'll not lose too much handling this way.
  6. Bluto

    Bluto Member

    I'm curious too, am OK with the slightly rough ride however the county roads where I live are poorly maintained and I'm afraid I'll eventually blow a tire and/or bend a rim, my GF blew a tire on a nasty pothole awhile back driving her stock Focus...but so far no problems driving the most excellent yet bumpy windy back roads locally, handling has been fantastic and the ride has been tolerable too ;-)
  7. Smokin

    Smokin Active Member

    I will most likely downgrade to 16" for winter snows and for summer AX competition.
    Will switch out with my OEMs in between...
  8. AlanBDahl

    AlanBDahl Active Member

    I'm considering 16" DWS tires for our Northwest rain/snow season but is like to locate some 16" Fiesta SES wheels rather than go aftermarket if possible.
  9. Sil3nt611

    Sil3nt611 Active Member

    With smaller wheels/larger sidewall tires you'll see a hit in handling. Not sure how much. If you never push the car to the limit anyway you may not even notice.
  10. Mike

    Mike Member

    That is What Tire Rack is recommending and I'm close to pulling the trigger.
  11. PCA-1

    PCA-1 Active Member

    On paper, higher diameter wheels and lower profile tires provide sharper turn in, thus lower diameter wheels and higher profile tires will be "less sharp" at turn in.

    As to the 205/40/17, I was totally surprised Ford chose this size as I knew the ride would be extra stiff.

    With a 16x7" wheel, you should drop a significant amount of weight per corner vs the stock 17x7. For instance, the 16x7 Team Dynamics Pro Race 1.2
    weighs 16.3 lbs, a reduction of 6.2 lbs per corner vs the stock 17x7 wheel's 22.5lbs . Each pound of rotational mass lost provides an equivalent performance gain of a 10 pound reduction in vehicle weight. Using the 16x7 Pro Race 1.2's 6.2lbs decrease in rotational mass, the loss in vehicle weight is 6.2 x 4 x10 = 248lbs. Braking is improved as the amount of heat generated when braking is lowered, and less heat also improves pad/rotor fade/wear.

    In general, lighter weight wheels give the suspension more control to keep the wheels planted resulting in better handling. A decrease in wheel diameter will locate the wheel weight closer to the hub, which makes the wheel easier to spin. The ice skater example can be used here as an ice skater spins faster with the weight of his arms close to the body and spins slower with arms extended from the body.

    I like to use the 5lb ball example when describing decreases in offset from stock. For example, hold a 5lb ball at your waist, then proceed to extend the 5lb ball horizontally away from your waist. It takes more muscle to hold the ball horizontal the further away from your waist the ball is extended. Because lowering offset moves the wheel weight outward from the stock position, it takes more power to spin the wheel.

    I took a quick look at available tires for the equivalent diameter as stock, lower diameter from stock, and higher diameter than stock. Before going any further, a short discussion on tire diameter. The stock tires have a set length of roll out, which is the distance the tire travels to reach one revolution. By lowering the diameter from stock, the shorter the distance the wheel travels to make one revolution compared to stock. Smaller diameters throw off speedometers, resulting in a higher mph readout vs actual. As well, smaller diameter setups affect gearing, resulting in the power band shifting to the lower end and decreasing top end. Conversley, when increasing the tire diameter from stock, the length of rollout increases, speedometer reads a lower speed than actual, and the top end is increased.

    With all that in mind, weight typically has the most influence in overall performance. If you are a purist, you can work out the best combination for the driving/performance level to suit your needs. For a daily driver looking for some ride improvement, a taller sidewall and/or smaller diameter wheel and larger sidewall, some performance improvement with lower weight, and a bit of widened stance for appearance if desired is a solid combination. If you auto-x, depending on the class, you will want to lose weight, lower diameter for more power down low, and pinch off a lower offset for a wider stance. For road racing, set ups vary more depending on the design of the circuit.

    What is best for most? For a street car wanting increased ride comfort and improve performance, I would recommend a smaller wheel diameter and lower tire/wheel weight, maintain as close to the stock overall diameter as possible, and increase tread width while keeping the offset up to 10mm less than stock. The wider tread width will more than offset the taller sidewall.

    Now the tire size...dropping down to a 16x7, while staying as close to stock overall diameter a 205/45/16 will net the same width as stock with a taller sidewall, with many tire options available. 215/45/16 will net a .39" increase in tread width and a taller sidewall, but few tires are available in this size. A 225/45/16 has a taller sidewall yet and an increase of tread width of .79", with few tire choices however.

    There are many online calculators to determine fitments. For comparing tire sizes and speedometer error I like to use this one as it is simple and gets the job done. Just put in tire sizes and select compare tire A to tire B. For changes in wheel width and offset, I use this calculator. If you play around with the calculators, you can zero in on what you want and check for availability of size by checking a variety of tire sites. Tire weight is also important to include in your search as well.

    If you guys are interested, I can look into a group buy for Team Dynamics 16x7 Pro Race 1.2 wheels. Pm your interest unless the OP is fine with member feedback.
    Last edited: Oct 22, 2013
    captainmorbid likes this.
  12. Mike

    Mike Member

    Wow. Awesome Explanation. Thank You
  13. PCA-1

    PCA-1 Active Member

    You are welcome Mike. Any questions/other, please let me know. :)
  14. AlanBDahl

    AlanBDahl Active Member

    There are plenty of 16 lb. 17" wheels out there too, indeed my 18x8 race wheels for my Solstice weigh 16 lbs. Going to a smaller wheel to save weight may make sense but IMHO the weight would need to be less than 16 lbs. to make the decision based solely on weight. Remember gearing is important too so the wheel/tire need to be evaluated as a package.
  15. Bluto

    Bluto Member

    One other (minor) consideration for going to 16" tires is that all things being equal (height and width) the 16" tire will be slightly heavier than the 17" and thus counteract some of the weight savings on the wheel...for example in Bridgestone RE760 a 205/40-17 is 20 lbs, a 205/45-16 is 21 lbs.
  16. Mayhem

    Mayhem Active Member

    Yeah, people do generally seem to forget about the tires. But if you pick wisely you'll shave off significantly more weight from the wheels, and the tire weight will be insignificant. Good to keep in mind for overall weight differences though.
  17. Mike

    Mike Member

    And 205 45 16 DWSs are 18 lbs. Things that make you go Hmm.
  18. Fistofthebrownstar

    Fistofthebrownstar New Member

  19. Fistofthebrownstar

    Fistofthebrownstar New Member

    not necessarily true at at. the shorter sidewall needs additional stiffening compared to a taller sidewall tire

    many 16 and 15 inch tires are the same weight as the 40 series 17 inch and some are even lighter
    audiphile likes this.
  20. audiphile

    audiphile Member

    I'm on 205/50/16. Ride quality is much improved. You can also run slightly lower PSI and not worry about bending wheels as much.. Turn in is not as sharp, but still sharper than any other car I've ever had, including my e36 M3, numerous VW's and etc. I don't think I'm going back to the stock 17's at all. I'm thinking of selling them and buying another set of 16's for track use, or just keeping them in the garage if I ever decide to sell the FiST
    Last edited: Dec 21, 2013
  21. ST_Rocky

    ST_Rocky Member

    One thing I don't understand, is why everyone keeps speaking about 45 series width tires? From what I remember, a 40 series would have a wider tread patch on the ground than a 45 series. Sure, you want to save on weight. But, you also want the most tread you can on the pavement for ultimate grip.

Share This Page