Rear tires
03-07-2016, 09:52 PM
#1
Pro
Thread Starter
Rear tires
I hate to post this because of all the posts that have come before but I would like answers from those how have or started out with a car like mine.
.
Tried to make this short but couldn't - sorry. I'm new at this and I need an economical way to get better traction on a supercharged 575 RWHP C5 running a A4 and 3.42 gears. I will be occasionally running a grudge race or going to the 1/8 mile strip which is located only about 5 miles from my home. I will be able to mount rears at home and drive the 5 miles to the strip. If I get lazy I might also leave them on for a couple of days at a time for around town cruising – no interstate.
I've read everything I could find on the forum about rear (drag) tires but I want to make sure I go in the right direction the first time. It's stock now with 17" polished thin spokes on front and 18" on the rear. I'm looking at going to 17" polished thin spokes on the rear with some DR's for the 1/8 mile. I have read that the 17's on the rear will allow better tire choices, more sidewall and thus potentially better traction. As a bonus and with the polished thin spoke 17's are on the rear my thin spoke rims still match all around – no obvious drag rim for others to wary of.
So, I did a few calculations to see how well the 17" would fit on the rear versus the 18's now mounted. My calculations show the outer edge of the 17" mounted on the rear will be .220 farther inboard than the current 18” and .780 farther from the inside fender liner than the current 18". This should allow for a wider tire fitment.
For example, if I use ET Street Radials my choices would seem to be:
If I go with a 17” rim on the rear I could mount the P295/45R17. That's if I fudge on the rim width because the approved rim width is 9.5-11.0 (My 17” rim is only 8.5”) . This tire has a 10.6” tread width and is 27.2” tall.
If I keep my 18” rim I could use the P305/35R18 That's if if I fudge on rim width because the approved rim width is 10.0-12.0 (My 18” rim is only 9.5”) . This tire has a 11.5” tread width and is 26.4” tall.
If I used ET Street S/S Radials my choices would seem to be:
If I go with a 17” rim on the rear I could use the P275/40R17. That's if I fudge on the rim width because the approved rim width is 9.0-11.0 (My 17” rim is only 8.5”) This tire has 10.3” tread width and is 26” tall.
If I keep a 18” rim I could use the P305/35R18. That's if I fudge on the rim width because the approved rim width is 10.0-12.0 (My 18” rim is only 9.5”) This tire has 11.2” tread width and is 26.6” tall.
1. What do you think about fudging on rim width by about .5” or so?
2. Using the above examples it appears if I go 17” (with C5 stock rim width) I can get more side wall but a more narrow tire. If I stay with 18” (with C5 stock rim width) I get less sidewall with a wider tire. Is this a correct assumption? If so which will I get the best track results with and which would you recommend - 17" or 18" rears? Or is there likely to be any measurable difference?
3. Gimmie some help .... what other tires would you suggest for using with the either the stock 17” (8.5") or the 18” (9.5") rims? I just pulled the Mickey's out of the air for the above example. Maybe Nito or someone else has a better size for my 17"s or 18"s?
Thanks in advance and please don't flame me for the question.
. Tried to make this short but couldn't - sorry. I'm new at this and I need an economical way to get better traction on a supercharged 575 RWHP C5 running a A4 and 3.42 gears. I will be occasionally running a grudge race or going to the 1/8 mile strip which is located only about 5 miles from my home. I will be able to mount rears at home and drive the 5 miles to the strip. If I get lazy I might also leave them on for a couple of days at a time for around town cruising – no interstate.
I've read everything I could find on the forum about rear (drag) tires but I want to make sure I go in the right direction the first time. It's stock now with 17" polished thin spokes on front and 18" on the rear. I'm looking at going to 17" polished thin spokes on the rear with some DR's for the 1/8 mile. I have read that the 17's on the rear will allow better tire choices, more sidewall and thus potentially better traction. As a bonus and with the polished thin spoke 17's are on the rear my thin spoke rims still match all around – no obvious drag rim for others to wary of.
So, I did a few calculations to see how well the 17" would fit on the rear versus the 18's now mounted. My calculations show the outer edge of the 17" mounted on the rear will be .220 farther inboard than the current 18” and .780 farther from the inside fender liner than the current 18". This should allow for a wider tire fitment.
For example, if I use ET Street Radials my choices would seem to be:
If I go with a 17” rim on the rear I could mount the P295/45R17. That's if I fudge on the rim width because the approved rim width is 9.5-11.0 (My 17” rim is only 8.5”) . This tire has a 10.6” tread width and is 27.2” tall.
If I keep my 18” rim I could use the P305/35R18 That's if if I fudge on rim width because the approved rim width is 10.0-12.0 (My 18” rim is only 9.5”) . This tire has a 11.5” tread width and is 26.4” tall.
If I used ET Street S/S Radials my choices would seem to be:
If I go with a 17” rim on the rear I could use the P275/40R17. That's if I fudge on the rim width because the approved rim width is 9.0-11.0 (My 17” rim is only 8.5”) This tire has 10.3” tread width and is 26” tall.
If I keep a 18” rim I could use the P305/35R18. That's if I fudge on the rim width because the approved rim width is 10.0-12.0 (My 18” rim is only 9.5”) This tire has 11.2” tread width and is 26.6” tall.
1. What do you think about fudging on rim width by about .5” or so?
2. Using the above examples it appears if I go 17” (with C5 stock rim width) I can get more side wall but a more narrow tire. If I stay with 18” (with C5 stock rim width) I get less sidewall with a wider tire. Is this a correct assumption? If so which will I get the best track results with and which would you recommend - 17" or 18" rears? Or is there likely to be any measurable difference?
3. Gimmie some help .... what other tires would you suggest for using with the either the stock 17” (8.5") or the 18” (9.5") rims? I just pulled the Mickey's out of the air for the above example. Maybe Nito or someone else has a better size for my 17"s or 18"s?
Thanks in advance and please don't flame me for the question.
03-08-2016, 11:25 AM
#3
If its truly only for the track, I have considered the same thing. I currently have 305/35/18 MT ET II DR's on mine.
For the track, I am leaning toward a 17" front wheel on the rear with a M&H slick (26x8.5x17).
My understanding, and the reason that I am leaning this way is that DR's are very hard on the drivetrain because there is no sidewall flex. However, slicks should have better flex and thus better traction and more shock absorption before breaking driveline components.
Of course, 16" would be better, more sidewall, etc, but you are pretty much limited to CCW's ($$$) in a 16" wheel, with some grinding of the control arm. Those 17"s by M&H are intriguing.
For the track, I am leaning toward a 17" front wheel on the rear with a M&H slick (26x8.5x17).
My understanding, and the reason that I am leaning this way is that DR's are very hard on the drivetrain because there is no sidewall flex. However, slicks should have better flex and thus better traction and more shock absorption before breaking driveline components.
Of course, 16" would be better, more sidewall, etc, but you are pretty much limited to CCW's ($$$) in a 16" wheel, with some grinding of the control arm. Those 17"s by M&H are intriguing.
Last edited by TX Z06 02; 03-08-2016 at 11:25 AM.
03-08-2016, 02:45 PM
#4
Pro
Thread Starter
Rear rims and tires
The reason I didn't propose using the 285/40-18 is that they are only 10.5 inches wide. Yes they are a better fit as far as allowed rim width but the 2 18" tires I proposed are wider.
My theory was to use the widest tire possible for the given 17" and 18" rim sizes/widths. Thus one of my questions was, to those with experience, is it OK to fudge on the allowed rim with by .5" or so and mount a slightly wider tire than the allowed rim width gives..
My theory was to use the widest tire possible for the given 17" and 18" rim sizes/widths. Thus one of my questions was, to those with experience, is it OK to fudge on the allowed rim with by .5" or so and mount a slightly wider tire than the allowed rim width gives..
03-08-2016, 02:56 PM
#5
Pro
Thread Starter
If you read my post closely you will see that I am looking for a tire that can be driven a short distance to the track and also used occasionally on the street for a short cruse in dry weather. Possibly even for some "spirited driving" with my friends the Mustangs, BMW's and so on. No interstate usage.
Also, I have not read that slicks are easier on parts. I would think they are harder on parts from a standing start. For the first few milliseconds as the slick "wraps up" it will be absorbing some shock but once fully "wrinkled" the slick should hook much better thus transferring more sudden shock to the drivetrain. Maybe I am wrong but would like to hear from experienced user on this.
Also, I have not read that slicks are easier on parts. I would think they are harder on parts from a standing start. For the first few milliseconds as the slick "wraps up" it will be absorbing some shock but once fully "wrinkled" the slick should hook much better thus transferring more sudden shock to the drivetrain. Maybe I am wrong but would like to hear from experienced user on this.
If its truly only for the track, I have considered the same thing. I currently have 305/35/18 MT ET II DR's on mine.
For the track, I am leaning toward a 17" front wheel on the rear with a M&H slick (26x8.5x17).
My understanding, and the reason that I am leaning this way is that DR's are very hard on the drivetrain because there is no sidewall flex. However, slicks should have better flex and thus better traction and more shock absorption before breaking driveline components.
Of course, 16" would be better, more sidewall, etc, but you are pretty much limited to CCW's ($$$) in a 16" wheel, with some grinding of the control arm. Those 17"s by M&H are intriguing.
For the track, I am leaning toward a 17" front wheel on the rear with a M&H slick (26x8.5x17).
My understanding, and the reason that I am leaning this way is that DR's are very hard on the drivetrain because there is no sidewall flex. However, slicks should have better flex and thus better traction and more shock absorption before breaking driveline components.
Of course, 16" would be better, more sidewall, etc, but you are pretty much limited to CCW's ($$$) in a 16" wheel, with some grinding of the control arm. Those 17"s by M&H are intriguing.
03-08-2016, 04:33 PM
#6
Safety Car
If I go with a 17” rim on the rear I could use the P275/40R17. That's if I fudge on the rim width because the approved rim width is 9.0-11.0 (My 17” rim is only 8.5”) This tire has 10.3” tread width and is 26” tall.
this is no prob.... ran those tires/wheels for a whole lotta passes...same size ....over several seasons... same gear ratio/A4 as yours' and a 3600 stall.... the 26" tire is a good choice and you should be able to hook up fine..I found the 27 and 28" tires too tall for an A4, OK for an M6 though... driving a few miles to the track with them mounted is no issue as well..... still racing the same tire size now btw but with a 9.5" wide rim but only 'cuz I got a deal on the rims....generally drive to the track with my front skinnies and DRs mounted, it's a 40 min drive for me, no issues, MT ET Streets....
oh and I do better with DRs than slicks as do pretty much all of my buds....... guys around here seem to agree that slicks work better for M6 cars and DRs work better for A4 cars....
this is no prob.... ran those tires/wheels for a whole lotta passes...same size ....over several seasons... same gear ratio/A4 as yours' and a 3600 stall.... the 26" tire is a good choice and you should be able to hook up fine..I found the 27 and 28" tires too tall for an A4, OK for an M6 though... driving a few miles to the track with them mounted is no issue as well..... still racing the same tire size now btw but with a 9.5" wide rim but only 'cuz I got a deal on the rims....generally drive to the track with my front skinnies and DRs mounted, it's a 40 min drive for me, no issues, MT ET Streets....
oh and I do better with DRs than slicks as do pretty much all of my buds....... guys around here seem to agree that slicks work better for M6 cars and DRs work better for A4 cars....
Last edited by dankhts; 03-08-2016 at 04:41 PM.
03-09-2016, 10:52 AM
#7
Also, I have not read that slicks are easier on parts. I would think they are harder on parts from a standing start. For the first few milliseconds as the slick "wraps up" it will be absorbing some shock but once fully "wrinkled" the slick should hook much better thus transferring more sudden shock to the drivetrain. Maybe I am wrong but would like to hear from experienced user on this.
Post #6: https://www.corvetteforum.com/forums...g-radials.html
Post #12: http://www.z06vette.com/forums/f5/drag-radials-115148/
Post #8: http://ls1tech.com/forums/wheels-tir...ag-radial.html
(from here)
Drag Radials
Not only have racers run quicker times with ET Street Radials than with ET Streets, M/T also openly admits that this is the case. So did the company shoot itself in the foot? Not exactly. While M/T's drag radials are proven performers, Ken says they are far less forgiving than standard bias-ply slicks. "Due to a drag radial's stiffer construction, they are not as reliable in regard to traction and recovery from spinning as a bias-ply tire," he explains. "Drag radials have the potential to be quicker, but can be very finicky, especially with a manual-transmission car. They generally require a much more time-consuming chassis setup."
The fact that you are an A4 helps. Yours has less drivetrain shock due to your torque/stall converter. So your results may be different.
I leave my MT ET II's on all the time. I am sure they will do fine at the track with my new power levels, and they are much better than street tires on the street. You mentioned going back to street tires for normal use, so thats why i mentioned the slicks as an alternative.
Also, dont shy away from narrower tires to fit your wheels as opposed to putting too much tire on the wheel. At your HP level, a narrower tire (275 width) will still hook just fine, weigh less and probably provide better ET on the track.
Last edited by TX Z06 02; 03-09-2016 at 11:02 AM.
03-18-2016, 11:46 PM
#8
Pro
You could pick up 2 C5Z front wheels pretty cheap and they are 17x9.5 then run the M/T ET Street R in 305/45/17. It's what I run and is the best drag radial i've tried to date. So far I've been down to a 1.38 60' on them in my TT C5Z auto.
2nd choice would be an M&H 275/50/17 drag radial and it would fit fine on your 17" rim. I went 1.40 60' on those in a supercharged C5Z auto.
2nd choice would be an M&H 275/50/17 drag radial and it would fit fine on your 17" rim. I went 1.40 60' on those in a supercharged C5Z auto.