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Plus sizing Tires (not wheels)

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#1
I am seriously considering going plus size on my winter tires for some increased tire wall. I take the ST to a lot of trailheads on pretty gnarly fire roads and have already observes some damage to the RPF1s.

...and, on the highway (70mph here), the FiST is pretty high in the Rev range for cruising. So this is what I am thinking:

Stock: 205/45R16
Plus: 205/55R16

This will increase overall diameter by 1.6" and wall by 0.8"... It doesn't appear so, but will I run into any clearance issues? If not, how large can I push the size?

*Edited for correct tire size
 


Ford ST

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#2
Did you mean a 215 instead? of the 255 that's a really wide Tire, and absolutely will not work at all. 215 50 16 is big as you can go without rub.

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OP
J_BadWOLF
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Thread Starter #3
Good catch: I meant 205/55R16

Ouch... That would have been a hell of a tire

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OP
J_BadWOLF
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Thread Starter #7
205 50 16 would be your friend. A 205 55 16 could rub.

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Any idea of hidden 'rub areas' to check. Clearance from everything when sitting looks golden (possibility to go bigger?!?). I am thinking suspension or body components I am not thinking of... Hmmm [emoji848]

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Ford ST

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#8
Any idea of hidden 'rub areas' to check. Clearance from everything when sitting looks golden (possibility to go bigger?!?). I am thinking suspension or body components I am not thinking of... Hmmm [emoji848]

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First rubbing spot is going to be your inner fender liners. What you have to consider is when you make turns, and hit bumps the measurement is not going to be the same as just sitting flat on a driveway. Not to mention winter tires have pretty meaty treads on them, that's going to add some height especially when new.

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OP
J_BadWOLF
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Thread Starter #9
Does the tire size not reflect lug protrusion?

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alexrex20

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#10
Not really. One company's 205/55-16 could be 31.8in tall and another company's 205/55-16 might be 31.1in. I would look at the manufacturer's specs for that exact tire and compare to that of your current tires. My cousin had 215/45-17 on his FiST and they rubbed at full compression, e.g. quick jolts on a speed bump or 3-wheeling into a steep driveway. A 205/55-16 should be taller than a 215/45-17, but again it depends on the manufacturer.
 


OP
J_BadWOLF
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Thread Starter #11
I will look. I am really trying to add about 1" to tire wall. It leaves me a good deal of compression space. Everything save a hard impact

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LILIKE16ST

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#12
If you wanna add an inch or more to the overall sidewall without being too tall go with 15s. Tires are usually cheaper too comparitively speaking
 


danbfree

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#13
So in the spirit of the original question: I actually like my stock black rims but was hoping to upsize AND drop a bit with the conservative Eibach springs... Has anyone done the exact combo of the Eibach springs with just a bump up to 215/40/17's and can report on any rubbing? TIA!
 


OP
J_BadWOLF
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Thread Starter #14
For some update, I reached out to [MENTION=180]FiestaST[/MENTION]rally and he is currently running a pretty tall tire. It seems anything 24.5" and up will begin to rub under full compression. I can't wait to give it a try and see how it sits. I have also looked into the option of going down to a 15" with 205/55r15 for the 4.4" sidewall and almost identical diameter as OEM (as suggested) but even going the cheap route with, say, sparco terras, we are talking $750 over the $350 for just tires.

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OP
J_BadWOLF
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Thread Starter #15
So in the spirit of the original question: I actually like my stock black rims but was hoping to upsize AND drop a bit with the conservative Eibach springs... Has anyone done the exact combo of the Eibach springs with just a bump up to 215/40/17's and can report on any rubbing? TIA!
To help put some context, I am running the Mountune coils, so if mine end up fitting, it may help answer your question as well

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danbfree

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#16
To help put some context, I am running the Mountune coils, so if mine end up fitting, it may help answer your question as well
Thanks, that will be good to know, the Mountune and Eibach are both made by Eibach and identical in drop BUT the Mountune is a bit stiffer I believe, should be close enough to get a good comparison...
 


OP
J_BadWOLF
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Thread Starter #17
This 1"... A 55r would definitely be pushing it...
This is the only mount that might be an issue that I can tell after checking all suspension and body components


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alexrex20

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#18
That is not an accurate representation though. Remember, the 1 inch increase is in overall diameter so if you are measuring Tire to Fender clearance you would only be adding .5 inches

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OP
J_BadWOLF
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Thread Starter #19
That is not an accurate representation though. Remember, the 1 inch increase is in overall diameter so if you are measuring Tire to Fender clearance you would only be adding .5 inches

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Yes, this is true. The overall diameter change from a 205/45 to a 205/55 is 1.6". So I am guestimating based on a 1" increase ( as apposed to the 0.8" actual) to sidewall for varience in manufacturers until I decide on which specific tire to run. Then I can look at specific manufacturing specs.

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