• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!


16x8 or 15x7/8?

Messages
41
Likes
10
Location
Florida
#1
I'm sure it's been answered in one of these numerous threads, but why choose one size over the other? I don't plan on tracking the car, but I would like to get involved in some autocross; aside from that, it's just a daily. Sway me in one direction, because I'm stuck between the two. I'd like a meaty tire look, and I'm on stock suspension (if that changes anything). Thanks in advance!
 


FiSTerMr

1000 Post Club
Messages
1,042
Likes
572
Location
NYC
#2
I'm sure it's been answered in one of these numerous threads, but why choose one size over the other? I don't plan on tracking the car, but I would like to get involved in some autocross; aside from that, it's just a daily. Sway me in one direction, because I'm stuck between the two. I'd like a meaty tire look, and I'm on stock suspension (if that changes anything). Thanks in advance!
16x8! 15" I feel takes away too much of what makes this car what it is.

2017 Magnetic FiST w/Recaros
 


Messages
66
Likes
49
Location
South Weber
#3
I really like how much more civilized running a 16x8 has made the car. Keep in mind that if you really want to get into Autocross that running an inch wider wheel than stock is gong to move you out of the H Stock class that the FiST is very competitive in.
 


Dpro

6000 Post Club
Messages
6,157
Likes
5,779
Location
Los Feliz (In the City of Angels)
#5
16x8 gives you a tire size with a decent sidewall. The problem wifh the stock 17 is we really do not have much room in our wells. They were never designed for running wider tires and bigger wheels. Ford pretty much crammed the 17’s in there.
A lot of guys run 15x8 because massive amount of tire choices for track use. It was/is a pretty common rim diameter even moreso than 16’s which were almost interim before a lot of manufacturers jumped on the 17 bandwagon then the 18.
Both 17 and 18’s have broad selections of tires as well but they are too large for our cars lol.

So if you want cheap and light weight , looks more like a Go Kart 15’s.
If you want still pretty damn cheap, less sizes but enough looks right on the car go 16’s.
I would say look at pics of the car with 15’s and 16’s lots of them get a feel for how it looks and make your decision. Thats what I did and I am going 16x8 +35.
 


Messages
166
Likes
147
Location
DFW
#6
The biggest advantage of a 15" wheel is the tire selection. You can get just about any extreme performance/track tire you want for a 15" wheel.

If you're not tracking the car and aren't trying to get a specific tire for your car, a 16" wheel will be closer to the overall diameter of the OEM tire. And it will look a little less "monster truck" if that matters.

The turn-in is worse with a 15" wheel than a 16" one. And a 16" wheel might be a tiny bit faster. But that doesn't bother me nearly as much as not having the tires I wanted did.

Sent from my H8314 using Tapatalk

Edit, I got sniped by Dpro, but he's saying the same thing: 15 is less ideal but has the tire choice for track cars.
 


Dpro

6000 Post Club
Messages
6,157
Likes
5,779
Location
Los Feliz (In the City of Angels)
#7
The biggest advantage of a 15" wheel is the tire selection. You can get just about any extreme performance/track tire you want for a 15" wheel.

If you're not tracking the car and aren't trying to get a specific tire for your car, a 16" wheel will be closer to the overall diameter of the OEM tire. And it will look a little less "monster truck" if that matters.

The turn-in is worse with a 15" wheel than a 16" one. And a 16" wheel might be a tiny bit faster. But that doesn't bother me nearly as much as not having the tires I wanted did.

Sent from my H8314 using Tapatalk

Edit, I got sniped by Dpro, but he's saying the same thing: 15 is less ideal but has the tire choice for track cars.
Lol late to the game. I was in a full 10 minutes before you I would not exactly call that a snipe. :LOL::LOL:
 


Messages
166
Likes
147
Location
DFW
#8
Lol late to the game. I was in a full 10 minutes before you I would not exactly call that a snipe. [emoji38][emoji38]
12 according to my phone, but it also didn't show your comment for 10 minutes so I'm not sure I trust it anymore.

Sent from my H8314 using Tapatalk
 


Messages
223
Likes
162
Location
Michigan
#9
I run 16x8 with 215/45 Federals

Coming down from 17" and having a little more sidewall is perfect for protecting my wheels because Michigan roads are really bad in spots.

Also I lost about 8lbs per corner with my set-up which it noticeable.
 


Messages
38
Likes
4
Location
Palm Springs
#11
I have 15x8 and I’m starting to shop for tires again and the selection isn’t as good as when I bought my rims, I’m thinking of going to 16x7 but not sure if I want to shell out the extra $
 


FiSTerMr

1000 Post Club
Messages
1,042
Likes
572
Location
NYC
#12
May I ask what tires you have on them? What does it take away specifically that you don't like?
I ended up staying stock, but was planning on running 205/45/16 on the dekas. BFGoodrich. That size is as close to stock diameter as you gonna get on 16 inch wheels. BFGoodrich run a little wider, so less stretch with the 8 inch wide wheels.

2017 Magnetic FiST w/Recaros
 


OP
S
Messages
41
Likes
10
Location
Florida
Thread Starter #13
I run 16x8 with 215/45 Federals

Coming down from 17" and having a little more sidewall is perfect for protecting my wheels because Michigan roads are really bad in spots.

Also I lost about 8lbs per corner with my set-up which it noticeable.
Any pics of the setup? I was looking at those federals as I can get a set for like $340 which isn't bad at all. How do they handle in the rain?
 


Messages
166
Likes
147
Location
DFW
#15
I know it may be hard to quantify, but how much worse is the turn in on the 15s?
I can't quantify it, but the car needed an extra fraction of a second to "take a set". If I autocrossed I might be able to give you more of a description, but on a road course I didn't give it much thought.

Sent from my H8314 using Tapatalk
 


FiSTerMr

1000 Post Club
Messages
1,042
Likes
572
Location
NYC
#16
I can't quantify it, but the car needed an extra fraction of a second to "take a set". If I autocrossed I might be able to give you more of a description, but on a road course I didn't give it much thought.

Sent from my H8314 using Tapatalk
I drove my friend's FiST with 15s (I think 205/50 or .../55) with summer dunlops ("z" something, I think), great ride, but suffered quite a bit on turn-in. The steering slowed considerably, and braking suffered... at least compared to my FiST with the stock rubber. YMMV

2017 Magnetic FiST w/Recaros
 


kevinatfms

Senior Member
Messages
870
Likes
914
Location
Germantown
#17
I drove my friend's FiST with 15s (I think 205/50 or .../55) with summer dunlops ("z" something, I think), great ride, but suffered quite a bit on turn-in. The steering slowed considerably, and braking suffered... at least compared to my FiST with the stock rubber. YMMV

2017 Magnetic FiST w/Recaros
Just swapped my 15x7 Sparco Terras with 205/50R15's back to my 17x7 FRPP "Rally" wheels with 205/40R17's due to a TPMS error in one of the 15" wheels.

I can say without a doubt that the 15's dumb the steering down quite a bit but braking is better with the lighter 15" setup.

Both wheels/tires have 200tw tires on them so its not a rubber issue. The lighter 15" wheels have less rotational mass on the hub/rotor for the caliper to clamp down on versus the 17's.

As far as turn in, its drastically better with the 17" wheels, even if they are heavier. It feels much more precise on initial and on follow through. So as you turn the wheel, the tire doesnt need to catch up to your inputs throughout a turn. The 17's make the car a point and shoot while the 15's need some input while you transition the wheel to keep the front end placed where you need it.

As far as tires, there are almost triple the performance tire selection in the 205/50R15 versus the 205/40R17 stock size. The shorter sidewall also changes the gearing quite a bit and you can really feel it when accelerating from a stop and out of corners.

To me the 15's are the way to go over a 17" setup as far as price, selection and weight. For steering feel and overall precise-ness, its the 17's hands down. Ill still continue to run the 15's though as the weight drop is significant over my 17" setup.
 


FiSTerMr

1000 Post Club
Messages
1,042
Likes
572
Location
NYC
#18
Just swapped my 15x7 Sparco Terras with 205/50R15's back to my 17x7 FRPP "Rally" wheels with 205/40R17's due to a TPMS error in one of the 15" wheels.

I can say without a doubt that the 15's dumb the steering down quite a bit but braking is better with the lighter 15" setup.

Both wheels/tires have 200tw tires on them so its not a rubber issue. The lighter 15" wheels have less rotational mass on the hub/rotor for the caliper to clamp down on versus the 17's.

As far as turn in, its drastically better with the 17" wheels, even if they are heavier. It feels much more precise on initial and on follow through. So as you turn the wheel, the tire doesnt need to catch up to your inputs throughout a turn. The 17's make the car a point and shoot while the 15's need some input while you transition the wheel to keep the front end placed where you need it.

As far as tires, there are almost triple the performance tire selection in the 205/50R15 versus the 205/40R17 stock size. The shorter sidewall also changes the gearing quite a bit and you can really feel it when accelerating from a stop and out of corners.

To me the 15's are the way to go over a 17" setup as far as price, selection and weight. For steering feel and overall precise-ness, its the 17's hands down. Ill still continue to run the 15's though as the weight drop is significant over my 17" setup.
You are right about the car stopping easier with less rotational mass, but the added flex from the sidewall is what i felt when applying the brakes hard. of course, if you add some air, you can counter much of the negative effects of the increased sidewall.

2017 Magnetic FiST w/Recaros
 


Messages
7
Likes
0
Location
Rochester Hills, MI, USA
#19
I run 16x8 with 215/45 Federals

Coming down from 17" and having a little more sidewall is perfect for protecting my wheels because Michigan roads are really bad in spots.

Also I lost about 8lbs per corner with my set-up which it noticeable.
im 207 miles in and already have michigan pothole curb rash, and now im definitely coming down on size. what wheels and specs?
 


FiSTerMr

1000 Post Club
Messages
1,042
Likes
572
Location
NYC
#20
Dodging potholes is part of the fun, no? [emoji12]

2017 Magnetic FiST w/Recaros
 


Ford Community Posts



Top