Guide to A6 tire options, updated 4/20/03
12-29-2001, 05:06 PM
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Guide to A6 tire options, updated 4/20/03
<center><img src="http://pictureposter.audiworld.com/17157/a6_tires_3.jpg"></center><p>
A few months ago, I created an Excel file to help me select a new wheel/tire package for my S8. It listed tires by size that someone might consider mounting on an A8/S8, but while keeping speedometer error, fender clearance problems, and cosmetic issues to a minimum. After posting it in the A8/S8 forum, the owner of an A6 4.2 asked to post a similar table for the A6, ... and this is it. I think the data is reasonably self-explanatory, but a few comments
1. The horizontal dotted lines group results in 1% increments of speedometer error. In my case, I wanted to stay within +/- 1%, and to keep the tire's radius within about 1/8" of the original tire. In this table, I "zeroed" the data around the 255/40-17, the optional tire for the A6 4.2.
2. Depending on the manufacturer, a tire's actual dimensions do vary both + and - from these theoretical calculations.
3. The load rating of a tire is more-or-less proportional to the amount of air in it, hence % volume difference from the 255/40-17. To some extent, you can compensate for lower internal tire volume by running higher tire pressure than originally specified, but I didn't want a front tire that would be overloaded.
4. The approved and design rim width was based primarily on data from Bridgestone and Pirelli; data from other manufacturers may vary slightly. Note that with the same width tire, the rim recommended gets wider as the tire profile gets lower.
5. All else being equal, a shorter sidewall height makes the tire more responsive; taller makes the wheel less vulnerable to pothole damage and improves the ride. Those tires with 3" sidewalls will probably feel very firm and perhaps harsh, especially on cars with a "sport" suspension.
6. When installing wider tires on wider wheels, custom offsets are usually necessary to avoid fender or suspension clearance problems.
Wilfred: Happy New Year
For the curious, the link is to the corresponding A8/S8 tire options.<ul><li><a href="http://www.audipages.com/upgrades/tiresizeoptions.html">Guide to A8/S8 tire options</a></li></ul>
A few months ago, I created an Excel file to help me select a new wheel/tire package for my S8. It listed tires by size that someone might consider mounting on an A8/S8, but while keeping speedometer error, fender clearance problems, and cosmetic issues to a minimum. After posting it in the A8/S8 forum, the owner of an A6 4.2 asked to post a similar table for the A6, ... and this is it. I think the data is reasonably self-explanatory, but a few comments
1. The horizontal dotted lines group results in 1% increments of speedometer error. In my case, I wanted to stay within +/- 1%, and to keep the tire's radius within about 1/8" of the original tire. In this table, I "zeroed" the data around the 255/40-17, the optional tire for the A6 4.2.
2. Depending on the manufacturer, a tire's actual dimensions do vary both + and - from these theoretical calculations.
3. The load rating of a tire is more-or-less proportional to the amount of air in it, hence % volume difference from the 255/40-17. To some extent, you can compensate for lower internal tire volume by running higher tire pressure than originally specified, but I didn't want a front tire that would be overloaded.
4. The approved and design rim width was based primarily on data from Bridgestone and Pirelli; data from other manufacturers may vary slightly. Note that with the same width tire, the rim recommended gets wider as the tire profile gets lower.
5. All else being equal, a shorter sidewall height makes the tire more responsive; taller makes the wheel less vulnerable to pothole damage and improves the ride. Those tires with 3" sidewalls will probably feel very firm and perhaps harsh, especially on cars with a "sport" suspension.
6. When installing wider tires on wider wheels, custom offsets are usually necessary to avoid fender or suspension clearance problems.
Wilfred: Happy New Year
For the curious, the link is to the corresponding A8/S8 tire options.<ul><li><a href="http://www.audipages.com/upgrades/tiresizeoptions.html">Guide to A8/S8 tire options</a></li></ul>
12-29-2001, 05:38 PM
#2
Thanks.I keep a similar tire bible in my Audi files, some notes.
285s wont fit with standard offset. I've got 275s for track tires and only 3/16" clearance in the front.
I agree on theoretical sizing, like buying jeans same sizes over different manufacturers could vary 3/8" in OD.
My next set of track tires I will reduce the diameter by 5% to try to overcome the tall gearing we have in the 4.2s.
I agree on theoretical sizing, like buying jeans same sizes over different manufacturers could vary 3/8" in OD.
My next set of track tires I will reduce the diameter by 5% to try to overcome the tall gearing we have in the 4.2s.
12-29-2001, 08:17 PM
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For non-sport 215/55-16 stock tires, a close match
might be 235/45-17 for upgraded performance.
The sidewall changes from 4.7" to 4.2"; the
radius 12.7", diameter 25.3" stay the same.
Circumf. goes from 79.5" to 79.6" and
revs/mile from 797.0 to 796.0; thus the
new tires would be 0.1% "too slow."
The sidewall changes from 4.7" to 4.2"; the
radius 12.7", diameter 25.3" stay the same.
Circumf. goes from 79.5" to 79.6" and
revs/mile from 797.0 to 796.0; thus the
new tires would be 0.1% "too slow."
12-29-2001, 10:30 PM
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So, let me ask for suggestions...
I have the stock Dunlop 6000's for the A6 4.2/17". I'd like to go as wide as 19" for the nice big contact patch on S-03 Pole Positions, if I can find decent looking rims, but am concerned about noise level. The Dunlop's get pretty noisy when Lincoln's head barely shows. I also want to avoid spacers or anything like that so I don't really know what's possible.
All comments appreciated, and thanks again to Randy. You A8/S8 guys are simply awesome!
All comments appreciated, and thanks again to Randy. You A8/S8 guys are simply awesome!
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12-30-2001, 08:36 AM
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Re: Suggestions...
Wilfred,
From Brian's comment, I assume he's running either the 275/30-19 or 275/35-18. Being on the conservative side, I probably wouldn't go beyond 265/30-19 with a 9.5" rim. Sorry, but not being familiar with A6 wheels, I don't know what offset would be required with the 9.5" rim.
I did notice on TireRack.com that they recommend the 255/30-19 on an 8.5" rim for the A6 4.2. I have two concerns with this --
1. The "91 load index" of this tire is on the low side, 1356 lb at max tire pressure. The 265/30-19 has a 1433 lb or "93 load index". The original 255/40-17 has a 1477 lb or "94 load index". A lower load rating will require higher tire pressure, especially in the front, and ride quality will suffer.
2. The 8.5" rim is narrower than the minimum recommended for this tire. At best, this wheel will not allow a flat, uniform tire patch in contact with the road.
The link below is my first impression of the 255/35-20 S-03 on my S8. The tread is very quiet .... significantly better than the Pirelli 210 Winter tires that I'm running now. I didn't wear down the tread very much before switching to the Pirelli's, so I don't know if the S-03's will stay quiet as they approach the wear bars. In any case though, these are great tires, especially under braking. I discuss other S-03 "creature comforts" in the link.
The only caveat with a 30 series S-03: The ride will be very firm, and you won't have much sidewall to protect the wheel from pothole damage.
Good luck,<ul><li><a href="https://forums.audiworld.com/a8/msgs/5405.phtml">S-03 on an S8</a></li></ul>
From Brian's comment, I assume he's running either the 275/30-19 or 275/35-18. Being on the conservative side, I probably wouldn't go beyond 265/30-19 with a 9.5" rim. Sorry, but not being familiar with A6 wheels, I don't know what offset would be required with the 9.5" rim.
I did notice on TireRack.com that they recommend the 255/30-19 on an 8.5" rim for the A6 4.2. I have two concerns with this --
1. The "91 load index" of this tire is on the low side, 1356 lb at max tire pressure. The 265/30-19 has a 1433 lb or "93 load index". The original 255/40-17 has a 1477 lb or "94 load index". A lower load rating will require higher tire pressure, especially in the front, and ride quality will suffer.
2. The 8.5" rim is narrower than the minimum recommended for this tire. At best, this wheel will not allow a flat, uniform tire patch in contact with the road.
The link below is my first impression of the 255/35-20 S-03 on my S8. The tread is very quiet .... significantly better than the Pirelli 210 Winter tires that I'm running now. I didn't wear down the tread very much before switching to the Pirelli's, so I don't know if the S-03's will stay quiet as they approach the wear bars. In any case though, these are great tires, especially under braking. I discuss other S-03 "creature comforts" in the link.
The only caveat with a 30 series S-03: The ride will be very firm, and you won't have much sidewall to protect the wheel from pothole damage.
Good luck,<ul><li><a href="https://forums.audiworld.com/a8/msgs/5405.phtml">S-03 on an S8</a></li></ul>