Effect of changing aspect ratio
Thread Starter
Junior Member
Joined: Aug 2022
Posts: 35
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From: Trussville, Alabama
AMG GLC 43
Effect of changing aspect ratio
I found some Michelin pilot sport all seasons for glc43 amg but the rears in 21 inches have an aspect ratio of 40 instead of the stock 35. Stock Fronts have 40 aspect ratio.
is there a downside to going to 40 aspect ratio on the rear? Would they fit? By my calculations it’s a 14 mm difference in height.
or is it better to go with a 295 width with 35 aspect ratio. Many seem to have done that. That height is 103 mm
Amazing such a common vehicle doesn’t have more tire choices
is there a downside to going to 40 aspect ratio on the rear? Would they fit? By my calculations it’s a 14 mm difference in height.
or is it better to go with a 295 width with 35 aspect ratio. Many seem to have done that. That height is 103 mm
Amazing such a common vehicle doesn’t have more tire choices
Out Of Control!!
Joined: Nov 2018
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From: San Francisco Bay Area
2019 C63CS
Yes, the main downside is that your speedometer will be off. Below is a link that lets you compare different tires and the effect they have on the speedometer reading. You should always stay with the same diameter. In case of AWD you also must ensure that the diameter of the front matches the diameter of the rear or you will likely damage the drivetrain over time due to rotational speed differences between the rear and the front. A certain tolerance is allowed to account for uneven tire wear between the front and rear tires.
https://tiresize.com/calculator/
https://tiresize.com/calculator/
Out Of Control!!
Joined: Nov 2018
Posts: 11,432
Likes: 5,342
From: San Francisco Bay Area
2019 C63CS
The issue is 21". That's the most aggressive, sporty setup for the GLC and the 21" OE tires plus aftermarket tires are all summer tires. If you want all-season, you need to go down a wheel size. The 20" wheels have winter, summer and all-season options.
Thread Starter
Junior Member
Joined: Aug 2022
Posts: 35
Likes: 2
From: Trussville, Alabama
AMG GLC 43
Several posts on this and other forums have attested to going up from 285 to 295 width and report no problems. Seems the 35 aspect ratio on these have a similar height to fronts. Opinion?
Out Of Control!!
Joined: Nov 2018
Posts: 11,432
Likes: 5,342
From: San Francisco Bay Area
2019 C63CS
As far as diameter is concerned 285/25/21 and 295/35/21 is within tolerance of tire wear. However, for driving in snow you rather want more narrow tires than wider tires.
