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View Full Version : Fitting 275/60/15 drag radials to my VY SV8


Brett SS
07-06-2011, 02:28 PM
Hey guys,

Just wondering if anyone has attempted to or has fitted 275/60/15 M/T drag radials onto the back of a VY sedan or similar. I have seen a few people running them on utes but not sure if anyone has successfully made them fit onto a sedan yet.

I went out to Heathcote last weekend and ran 10.75@129mph but had a couple of little issues with belt slip at the top of 1st/2nd (probably cost a tenth or so) and I was hitting overdrive before the traps which hurts a few tenths and mph also. This was done on M/T 26/8.5" slicks on 15x8" interceptors and from looking through my logs in comparison to the last time I raced on 235/60/15 M/T drag radials it's shifting around 4km/h earlier at the same rpm which is probably due to a difference in the overall diameter and construction of the tyre.

My plan is to hopefully go back to drag radials as I felt they worked better overall than the slicks but I need to go as tall and as wide as possible that will fit under the guards. I will be getting poly air-bags to fit into the springs from the states so I can control the squat but I'm still wondering if they will fit anyway. The inner guards are cut out already so they don't need to be rolled either. I've seen people running 255/60/15's plenty of times with success so I know I could fit them which will give another 1" diameter but I'm hoping to fit the bigger 275/60/15's which will give 2" more over what I run currently.

My current combo is a VY SV8 with a PWR122 blower running 10-11psi, VCM Suite stage 5-SC cam, Patriot Performance LQ9 heads, 4500rpm hi-stall, 4.11 gears, twin 3" exhaust etc. It runs standard FE2 springs front and rear, standard FE2 rear shocks and adjustable Koni 90/10's in the front. It also has adjustable eccentric control arm bushes in the rear which have been adjusted to give as much tyre contact patch on launch. I've placed a list from Mickey Thompson of the 26/8.5" slicks next to the 3 drag radial sizes that are in this discussion so you can see the differences in sidewall widths, tread withs and diameter. I've also put a few pics from the weekend showing the squat and guard clearance I have now with the current setup.

I know one option is to swap out my gearing back to 3.73's but I actually really like the current combo so am trying to make this setup work rather than change gearing. Any help is appreciated as I think it can go a decent bit quicker with the current combo with the right tyre choice to stop it hitting overdrive.

Part Size Sidewall Width Tread Width Diameter Circ.
3052 26.0/8.5-15 9.9 8.1 25.9 82
3752R P235/60R15 9.5 8.4 26.1 82
3756R P255/60R15 10.1 9.0 27.1 85
3754R P275/60R15 11.0 9.5 28.0 87

http://i958.photobucket.com/albums/ae68/RedlinePhotography_2009/Heathcote%20Test%20And%20Tune%2029th%20May%202011/IMG_0188.jpg

http://i958.photobucket.com/albums/ae68/RedlinePhotography_2009/Heathcote%20Test%20And%20Tune%2029th%20May%202011/IMG_0440.jpg
STATIE
07-06-2011, 04:24 PM
I might be wrong here but I reckon you'll go backwards with the drag radials over the slicks, even in that size if you can get them to fit - have you thought about going a 28 X 9" slick - they will definately fit with guard work.

The 28's will murder any 26' high tyre for grip due to the extra height & also give you a few extra revs/mph to play with at the top end.
deano23x
07-06-2011, 05:15 PM
random question but what RWKW is ya car? cheers
dogsballs
07-06-2011, 06:13 PM
i think the radials will suit the auto betterer. but opinions are like assholes, everyone has one.
STATIE
07-06-2011, 07:48 PM
Yeh - you may be right - I just found that at around the 10 flat & 130 mph mark DR's just didn't cut it anymore.
I used to run the 275MT's so I know they fit a ute - but don't know about a sedan - being 28's they will do the job if you can make them fit - I just prefer slicks nowadays.
MR GMH
07-06-2011, 09:33 PM
What are your 60fts like Brett SS ?
VYSHSV8
07-06-2011, 09:41 PM
i might be wrong here but i reckon you'll go backwards with the drag radials over the slicks, even in that size if you can get them to fit - have you thought about going a 28 x 9" slick - they will definately fit with guard work.

The 28's will murder any 26' high tyre for grip due to the extra height & also give you a few extra revs/mph to play with at the top end.
+2 :):)......................
Brett SS
08-06-2011, 01:11 PM
random question but what RWKW is ya car? cheers

Last time I had it on the dyno it made around 380rwkw but I've made a few changes since which should have it up closer to 400rwkw. I'll try and get it back onto the dyno in the next few weeks.


What are your 60fts like Brett SS ?

My 60' times on the day were 1.57 seconds. I was happy with that as it was pretty much the same as most of the trailered drag cars on the day.


Yeh - you may be right - I just found that at around the 10 flat & 130 mph mark DR's just didn't cut it anymore.
I used to run the 275MT's so I know they fit a ute - but don't know about a sedan - being 28's they will do the job if you can make them fit - I just prefer slicks nowadays.

I found the 235/60 drag radials too small in the contact patch for what I need, but would the extra inch of tread width and the extra height be enough with my combo or do you still think it will spin? Going to a 28x9" M/T slick is another option for me as they will fit easier than the 275/60 drag radials as they are 27.3" tall compared to the drag radials at 28".
deano23x
08-06-2011, 01:33 PM
Thanks for the reply Brett! I'm hopeing to run my 380rwkw Monaro in the near future and really wanna run a 10 number! Your slicks info is good will help me out too
Brett SS
08-06-2011, 02:17 PM
Thanks for the reply Brett! I'm hopeing to run my 380rwkw Monaro in the near future and really wanna run a 10 number! Your slicks info is good will help me out too

Have you got slicks and front runners sorted out for your car yet? Being a manual you will need them...
STATIE
08-06-2011, 04:24 PM
Just to give you some idea Brett - I went from a 26' high slick running 10.5@130 ish NA all over the track skidmarks in the undies runs to a 28' slick same brand & width running in the 9's on gas @ 140+ dead straight almost boring going down the track - massive difference going up 2' in sidewall traction wise.

235 MT DR's I dunno how people run fast (11.00 & under) on - even my missuses car just burns them off the rims.
The 275's I used to use when I was running in the low 11's & were fine with that - dunno about the times you are looking for though.
dogsballs
08-06-2011, 05:57 PM
statie, with the 235's there still is a bit of an art to see what suspension, what pressure and how you ride/flash the stall to get out the hole.

thing is you look on the ls1.tech and there are more and more people going to radials (in auto's). there is a reason.
deano23x
08-06-2011, 06:33 PM
Have you got slicks and front runners sorted out for your car yet? Being a manual you will need them...

at the moment i am getting some 205/15 interceptor front runners from my mate but am unsure what to use on the rear? some 245/15 slick on interceptors?
PDFAST
10-06-2011, 10:44 PM
Just to give you some idea Brett - I went from a 26' high slick running 10.5@130 ish NA all over the track skidmarks in the undies runs to a 28' slick same brand & width running in the 9's on gas @ 140+ dead straight almost boring going down the track - massive difference going up 2' in sidewall traction wise.

235 MT DR's I dunno how people run fast (11.00 & under) on - even my missuses car just burns them off the rims.
The 275's I used to use when I was running in the low 11's & were fine with that - dunno about the times you are looking for though.

that must be why im stuck on 11.00 lol
10s at calder maybe on sat 25th one strike and im out
STATIE
11-06-2011, 10:20 AM
that must be why im stuck on 11.00 lol
10s at calder maybe on sat 25th one strike and im out

Nah - that's because you have a shit tuner.:)

Oh - and I reckon your converter could be a bit dodgy as well.
RIDE:42
11-06-2011, 12:26 PM
Nah - that's because you have a shit tuner.:)

Oh - and I reckon your converter could be a bit dodgy as well.

Gloom and Doom ?:rofl:
STATIE
11-06-2011, 06:47 PM
Gloom and Doom ?:rofl:

Uh uh - the one with the cross eyed cats.:1peek:
blnls1
11-06-2011, 06:54 PM
Off topic but anyone going to heathcote tomorrow????
PDFAST
25-06-2011, 11:51 PM
Nah - that's because you have a shit tuner.:)

Oh - and I reckon your converter could be a bit dodgy as well.

nar great tuner and great tce converter
pb at calder 10.87@128mph backed it up with a 10.88@128mph :smilesandbanana:
7lbs boost full weight on et streets not to shabby
better get the grange and that great tce converter goin soon greg :1peek: