Increasing ground clearance

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Thread: Increasing ground clearance

  1. #1
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    Increasing ground clearance

    Hello everyone,
    This may look like a silly question but since i have no experience is such issue i have to ask
    I need to increase the ground clearance of my car in a way that dose not affect the car handling, my car comes with 16" rims and i was thinking to have 17" , would that actually increase the ground clearance by 1" ?

    thanks in advance.

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  3. #2
    Moderate Moderator Steve in Chicago's Avatar
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    The rim diameter and the tire outer diameter and the suspension height are three different things.

    You can go from a 15" up to a 20" rim and choose a tire size that still has the same outside diameter (and height). The car won't be any higher or lower. The suspension geometry will be the same. The speedometer and odometer won't be affected. You'll have a shorter tire side-wall so the ride will be harsher and the rims will have less tire cushion to protect them from potholes.

    You can keep your same 16" rims but switch to a tire size that has a larger outside diameter and is taller. This will raise the car. The suspension geometry will be the same. The speedometer and odometer reading will be affected. You'll have a taller tire side-wall so the ride will be smoother and the rims will have more tire cushion to protect them from potholes.

    You can switch to taller springs. VW offered a rough road spring option that raised the car slightly. Do some searches on the subject to find out more about that setup. The suspension geometry will be altered. As with any geometry change, the further you go from the stock configuration, the more problems you run into. Read up on the guys that have altered suspension to go lower. With extreme lowering, the camber angles change and can't be easily (read: inexpensively) corrected. The same thing would go for extreme raising. With the VW rough road springs, the car only raises a bit so geometry changes are slight. The speedometer and odometer won't be affected.

    The least expensive solution for you would be to get taller 16" tires. I don't know how tall you can go before running into clearance issues. Check the clearance between the tire and the upper control arms. That's probably going to be your first limiting factor.

    If you need more height than that, the next step would be taller springs or adjustable springs like a coil-over system. Most coil over systems are designed to to allow you to drop the car, but depending on the kit you choose, can also raise the car too.
    mshamy likes this.

  4. #3
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    More ground clearance will negatively alter the cars handling because it raises the center of gravity. The degree of side effects varies with the amount of increase and the model of the car.

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    SuperCooled30V Moderator keithwbloom's Avatar
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    It is possible your car came with 205/55R-16s. By that profile, your rolling diameter is 16" + 2*(205mm * 55%). 16" = 406.4mm so 406.4mm + 2*112.75mm = 620.9mm. Half that is ~310.45mm or your nominal wheel radius to the ground (not accounting for squish).

    Using the same formula, if you kept the same width (205mm) then increasing aspect ratio to 60 will gain you an additional 2*5% or 20.5 mm. Half of that would be 10.25mm. So getting larger tires on your 16s will gain you about a centimeter of clearance.

    It's just repetitive math after that. Here's a chart that you might find helpful:

    Rim Width Aspect Rolling Dia. (mm) Radius (mm) Clearance Change (mm)
    16 195 55 620.9 310.45 -5.5
    16 195 60 640.4 320.2 4.25
    16 195 65 659.9 329.95 14
    16
    205
    55 631.9 315.95 0
    16 205 60 652.4 326.2 10.25
    16 205 65 672.9 336.45 20.5
    16 215 55 642.9 321.45 5.5
    16 215 60 664.4 332.2 16.25
    16 215 65 685.9 342.95 27
    17 205 50 636.8 318.4 2.45
    17 205 55 657.3 328.65 12.7
    17 205 60 677.8 338.9 22.95
    17 215 50 646.8 323.4 7.45
    17 215 55 668.3 334.15 18.2
    17 215 60 689.8 344.9 28.95
    17
    225 45 634.3 317.15 1.2
    17 225 50 656.8 328.4 12.45
    17 225 55 679.3 339.65 23.7
    17 225 60 701.8 350.9 34.95

    B7 S4 Cabriolet 6MT, 8P A3 Tip, B5.5 SC/IC V6 5MT

  7. #5
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    Quote Originally Posted by GALVANIZEDYANKEE View Post
    More ground clearance will negatively alter the cars handling because it raises the center of gravity. The degree of side effects varies with the amount of increase and the model of the car.
    less ground clearance will negatively alter the car's handling because it screws up the suspension geometry.

    Quote Originally Posted by mshamy View Post
    Hello everyone,
    This may look like a silly question but since i have no experience is such issue i have to ask
    I need to increase the ground clearance of my car in a way that dose not affect the car handling, my car comes with 16" rims and i was thinking to have 17" , would that actually increase the ground clearance by 1" ?

    thanks in advance.
    I'd check to see if VW offers a "Rough Road" suspension.... they offer it in certain cars for certain markets, where additional ground clearance is needed. Then maybe check to see if you can get the new B7 Passat Alltrack springs.
    mshamy likes this.

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    Question

    Quote Originally Posted by keithwbloom View Post
    It is possible your car came with 205/55R-16s. By that profile, your rolling diameter is 16" + 2*(205mm * 55%). 16" = 406.4mm so 406.4mm + 2*112.75mm = 620.9mm. Half that is ~310.45mm or your nominal wheel radius to the ground (not accounting for squish).

    Using the same formula, if you kept the same width (205mm) then increasing aspect ratio to 60 will gain you an additional 2*5% or 20.5 mm. Half of that would be 10.25mm. So getting larger tires on your 16s will gain you about a centimeter of clearance.

    It's just repetitive math after that. Here's a chart that you might find helpful:

    Rim Width Aspect Rolling Dia. (mm) Radius (mm) Clearance Change (mm)
    16 195 55 620.9 310.45 -5.5
    16 195 60 640.4 320.2 4.25
    16 195 65 659.9 329.95 14
    16
    205
    55 631.9 315.95 0
    16 205 60 652.4 326.2 10.25
    16 205 65 672.9 336.45 20.5
    16 215 55 642.9 321.45 5.5
    16 215 60 664.4 332.2 16.25
    16 215 65 685.9 342.95 27
    17 205 50 636.8 318.4 2.45
    17 205 55 657.3 328.65 12.7
    17 205 60 677.8 338.9 22.95
    17 215 50 646.8 323.4 7.45
    17 215 55 668.3 334.15 18.2
    17 215 60 689.8 344.9 28.95
    17
    225 45 634.3 317.15 1.2
    17 225 50 656.8 328.4 12.45
    17 225 55 679.3 339.65 23.7
    17 225 60 701.8 350.9 34.95

    Thank you very much, but my recommended 17" tire size is 235/45 ..who much clearance would i get?

  9. #7
    SuperCooled30V Moderator keithwbloom's Avatar
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    Quote Originally Posted by mshamy View Post
    Thank you very much, but my recommended 17" tire size is 235/45 ..who much clearance would i get?
    Rim Size Tread Width (mm) Aspect Ratio Rolling Dia. (mm) Radius (mm) Clearance Change (mm) Rolling Circ. (mm) Speedo Error (unadjusted) True Speed (100KmH Indicated)
    16 205 55 631.9 315.95 (5.5) 1,985.2 0.017 98.3
    16 205 60 652.4 326.2 4.8 2,049.6 (0.015) 101.5
    16 205 65 672.9 336.45 15.0 2,114.0 (0.047) 104.7
    16
    215 55 642.9 321.45 0.0 2,019.7 (0.000) 100.0
    16 215 60 664.4 332.2 10.8 2,087.3 (0.033) 103.3
    16 215 65 685.9 342.95 21.5 2,154.8 (0.067) 106.7
    16 225 50 631.4 315.7 (5.8) 1,983.6 0.018 98.2
    16 225 55 653.9 326.95 5.5 2,054.3 (0.017) 101.7
    16 225 60 676.4 338.2 16.8 2,125.0 (0.052) 105.2
    17 225 45 634.3 317.15 (4.3) 1,992.7 0.013 98.7
    17 225 50 656.8 328.4 6.9 2,063.4 (0.022) 102.2
    17 225 55 679.3 339.65 18.2 2,134.1 (0.057) 105.7
    17 235 40 619.8 309.9 (11.6) 1,947.2 0.036 96.4
    17
    235 45 643.3 321.65 0.2 2,021.0 (0.001) 100.1
    17 235 50 666.8 333.4 12.0 2,094.8 (0.037) 103.7
    17 245 40 627.8 313.9 (7.6) 1,972.3 0.023 97.7
    17 245 45 652.3 326.15 4.7 2,049.3 (0.015) 101.5
    17 245 50 676.8 338.4 17.0 2,126.2 (0.053) 105.3
    17 255 40 635.8 317.9 (3.6) 1,997.4 0.011 98.9
    17 255 45 661.3 330.65 9.2 2,077.5 (0.029) 102.9
    17 255 50 686.8 343.4 22.0 2,157.6 (0.068) 106.8

    IIRC, at least in B5.5s with Climatronic, I believe you can adjust rolling circumference to correct speedo error. Dunno about B6s.

    mshamy likes this.
    B7 S4 Cabriolet 6MT, 8P A3 Tip, B5.5 SC/IC V6 5MT

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