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Wheel Size, Offset & Tire Information

Handy Andy

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2018 Ford Fiesta SE HB
#21
Remember the 195/50 is 50% sidewall height of that 195 number versus 195/60 having 60% of that same 195 value - you have MORE percentage (60% versus the 50%) of sidewall.

From a person that has had potholes cut thru a sidewall of a tire, it does not happen as often now but when carcasses for the tire itself were made out of natural materials - versus the synthetics used now - Radial or Bias ply - the more tire you have between you and the road surface gives you and your whole car a little less shock value and both you and your car won't need as much Chiropractic therapy later.
 

Handy Andy

Senior Member
Premium Account
Messages
432
Likes
401
City
Grand Rapids
State
MI
Country
United States
What I Drive
2018 Ford Fiesta SE HB
#22
The stock wheels on my fiesta are also 195/50r16 with a +42mm offset; I was wondering if someone knows if a 205/50r16 say a +40mm or +38mm or a 205/45r16 would fit without . I mainly want to try and get a bit more rubber for a softer ride and try to fill up the wheel wells as much as I can with just rims and tires.
Thats a tough call, for you really need to also look at the RIM WIDTH - not just Offset.

IN a typical 15" the steel rim width is 6"

IN any tire rim above 15" for FORD using 108mm (4.25 inch bolt pattern) it's spreads out to 6.5" wide (6-1/2") and wider
  • so that affects the "ballooning" of the wheel and tire appearance
  • Offset is just the push or pull in from the "natural" CASTER (the tip-in/out or knife in) edge.
    • Where the contact point of tilt out or in of the wheel is - just below the bearing and steering knuckles' rotation axis.
    • Changing offset will make the tires' contact point change - so wider tire and rim size have to be kept within a range so as you steer, you or your vehicle are not fighting each other or the road - by causing tire scrub - that will waste a good gummy tread pretty fast.
      • this is above and beyond the typical rub or scrape from extreme angle turns
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The wider the tire - the more curve (balloon) it will have in an effort to squeeze into the width of the rim to seat its bead.
  • In some cases, its 'a more preferred method (the curve or pucker of the balloon) using a narrow rim works in your favor for reducing road footprint contact under lighter loads to help with rolling efficiently to road resistance - you handle the rest by inflation pressures and noble gasses used if you're on track.
You have two things to worry about - the outer fender and inner wheel-well - on top of the changes in geometry in both Caster and Camber and the ability of the wheel to turn or rotate thru the turn and the amount of torque the steering pump will have to force the wheel against the force of the road against it.

The wider the tire- the more that scrub effect and the CAMBER (tippy-toe out or in, not just Toe-in or out) and where that force is at in the radius of the turn - will seriously affect handling. The lower control arm is only going to have so much distance or throw to work with - you'll hear clunks from the bottoming out caused by the ultra-wide tire against the throw length the control arm. Although not a big deal - you also don't want to shred the tire either on the fender just trying to handle a sharp curve at highway speeds.

At current height - even a 225-45 17 is a bit much - you actually need to RAISE the car to handle the dive even with the sway bar and upgraded bushings.
 

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