Jump to content

Tyre Size and Differential Failure: 245/35/20 and 325/30/21


Recommended Posts

Greetings, everyone...I bought the Signature Forged SV310s in 20/21 from Fasthawk on this forum.I want to have all of them repainted in Gloss Black and install red fasteners on the back.

Specifications: 20x9 with an offset of ET32.
The dimensions of the object are 21 inches in width, 12 inches in height, and have an offset of 32 millimetres.

I have a question...

1) I have heard that if I raise the size of the tyre sidewall uniformly, I should anticipate the failure of the rear differential bearing.Expanding the tyre size to 245/35/20 and either 305 or 325/30/21...In my previous 2015 R8, I successfully enlarged the dimensions of the walls on my 20" ADV1 wheels without encountering any problems. However, my luck took a turn for the worst when I was struck by a drunk motorist who ran a red light while travelling at a speed of 35 miles per hour.What are your opinions or reflections on this matter?I prefer the use of larger sidewalls to reduce the potential hazards posed by the poor road conditions in Houston and to limit the amount of noise that enters the cabin of the vehicle.

All feedback is highly valued and welcomed.

Link to comment
Share on other sites

Thank you for the information, everyone. Please refer to the text below.The factory Audi Setup seems to exceed the 5% threshold, but the generally used combination exceeds 6.24%. It is possible that there is an error margin, considering the superior knowledge of Audi engineers compared to mine.I will proceed with my current configuration and inform all of you about the outcome.My vehicle, a 2017 Base model, will not be lowered.Please verify the figures, although I believe they are accurate.

    The front tyres have a size of 245/30/20, while the rear tyres have a size of 305/30/20. These tyre sizes are the ones originally installed by Audi. The difference in diameter between the front and rear tyres is 5.50%.
    The front tyres have a size of 245/35/20, while the rear tyres have a size of 305/30/21. The difference in diameter between the front and rear tyres is 5.43%.
    The front tyres have a size of 255/35/20, while the rear tyres have a size of 305/30/21. The difference in diameter between the front and rear tyres is 4.36%.
    The front tyres have a size of 255/35/20, while the rear tyres have a size of 315/30/21. The difference in diameter between the front and rear tyres is 5.23%.
    The front tyres have a size of 245/30/20, while the rear tyres have a size of 325/30/21.
        Difference in diameter: 11.21%
    The front tyres have a size of 245/35/20, while the rear tyres have a size of 325/30/21. The difference in diameter between the front and rear tyres is 7.20%.
    The front tyres have a size of 255/35/20, while the rear tyres have a size of 325/30/21. I have decided to choose the following option: the difference in diameter is 6.10%.
    The front tyres have a size of 245/30/20, while the rear tyres have a size of 325/25/21. This combination is often used.
        Difference in diameter: 6.24%

Link to comment
Share on other sites

Note that the first and second generations of R8 vehicles have distinct Quattro systems, with the first using a viscous coupling system and the latter employing a Haldex system. The gen2 model has increased tolerance to variations in diameter, as seen by the compatibility with a wider range of standard tyre sizes.

Link to comment
Share on other sites

As long as you maintain a narrow margin of 5.5% deviation from the stock value, with a range of +/-1%, the differential will not pose any issues. However, due to the increased width of the front tyres and their higher profile, it is likely that the front tyres will come into contact with the wheel liners when turning, causing rubbing. while I had my vehicle equipped with original equipment manufacturer (OEM) 20-inch wheels and the ride height was adjusted with 15mm spacers, the tyres made contact and caused friction while turning. Given the addition of your ET, bigger rims, and higher and wider tyres, it is likely that you may experience some rubbing.

Link to comment
Share on other sites

The standard tyre sizes are determined based on the appropriate gearing to ensure that the entering axles maintain the same speed in the differential, despite the greater rolling diameter of the rear axles.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...