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Wheel and tyre size
Rogthebandit - 15/2/12 at 08:45 PM

Hello

I have been looking through the old threads for details on wheel and tyre sizes and which would be the best size for my mk with a gsxr 1000. I m running a 3.62 diff. Any advice or a pointer towards any previous threads would be much appreciated.

Cheers
Rog

RJK350 - 15/2/12 at 08:52 PM

I am running 13 inch wheels. Front tyres 185/60/13 and rear 205/60/13 on my MK Indy Aprilia.
Smaller wheels, less weight to spin and to brake.

All the best Rob

whitestu - 15/2/12 at 09:11 PM

I've just swapped from 15" to 13" wheels and the car feels a lot better.

JoelP - 15/2/12 at 09:19 PM

If you do go to 13", check that they will clear your brakes.

PAUL FISHER - 15/2/12 at 09:22 PM

Agree with Rob, thats your best option, 13" wheels 7" wide et 35 centre bore 63.5mm, but due to Sierra rear brakes your options are limited to which ones will fit, I know Compomotive CXR's and Team dynamic's pro race 1.2's will fit with mods to rear handbrake spring, alot of the minilight/superlights etc in 13" don't, due to the way they are constructed.
Another common size for the Indys is 15" thats what I ran on my last Indy, again 7" wide ET 35, a good tyre size for these would be 195 50 15 or 195 55 15 or 205 50 15 the choice is yours.



[Edited on 19/05/04 by PAUL FISHER]

Rogthebandit - 15/2/12 at 09:35 PM

Cheers for the info everyone. I have seen some nice wheels on eBay 13" . I will need to do a bit more investigation as you mention regarding the clearance on the ford brakes.

Whitestu, was there a big difference in the acceleration or noticeable power difference going from 15 to 13 inch?

Rog

RJK350 - 15/2/12 at 09:45 PM

Roger,

If you are running Sierra calipers on the back, the hand brake spring fouls on the inside of the rim (Team Dynamics Pro 1.2 wheels). I had some special springs made that fit and do not foul. If you go that way U2U as I have some springs left.
Running Wilwood calipers on the front, with no clearance issues.

Rob

Rogthebandit - 15/2/12 at 09:47 PM

quote:
Originally posted by RJK350
I am running 13 inch wheels. Front tyres 185/60/13 and rear 205/60/13 on my MK Indy Aprilia.
Smaller wheels, less weight to spin and to brake.

All the best Rob



Rob, I was just checking out your picture of the rear brake, looks tight. Are you using ford calipers on the front and rear? What type of wheel are yours. They look well

Rog

Rogthebandit - 15/2/12 at 09:50 PM

Lol Rob, you've answered my questions before I posted them

daniel mason - 15/2/12 at 09:50 PM

i would not personally run 13" rims with that diff ratio. it will top out quicker than a 205/50/15.
a 13" wheel and tyre combo would defo be better but i'd look into swapping or p/x for a 3.38 ford diff.

PAUL FISHER - 16/2/12 at 12:04 AM

quote:
Originally posted by daniel mason
i would not personally run 13" rims with that diff ratio. it will top out quicker than a 205/50/15.
a 13" wheel and tyre combo would defo be better but i'd look into swapping or p/x for a 3.38 ford diff.



Its going to make next to no difference Daniel, if he runs the 13" wheels with the 205 60 tyres compared with the 15"' 205 50 tyres the diameters are almost the same, just 2mph difference at 125mph.

whitestu - 16/2/12 at 12:44 PM

quote:

Whitestu, was there a big difference in the acceleration or noticeable power difference going from 15 to 13 inch?



Neither were noticable, but there is a huge difference in how the front suspension works over bumps. With the admittedly quite heavy 15" wheels the front wheels moved an awful lot which made the car feel less stable over bumps.

With the lighter 13" wheels the car is much more composed and the steering feel is better.

Bear in mind though that I changed from heavy TSW 15" wheels and Yoko A539 tyres to light weight TD wheels and Toyo R888s.

Stu

loggyboy - 16/2/12 at 01:01 PM

Has anyone weighed up the real weight difference betweem 13s and 15s whe using equivlent circum. tyres?
Ive always felt that the big profile of rubber you get with 13s would come close to equalising the amount of extra metal you get with 15s. I know rubber is pretty heavy and makes up a fair percentage of the total wheel/tyre weight combo.
I know its hard to compare as there arent many (if any) identical make/style wheels that come in 13s and 15s, but has anyone acctually tried?

rost - 16/2/12 at 01:20 PM

I've made a comparison between 15" TD Pro Race 1.2s and 13" Compomotive CXRs rims and R888 tyres.
Funnily enough, the 13" R888s are lighter than the 15" ones!

Team Dynamics Pro Race 1.2
Dim: 15x7J + 195/50/15
Rim: 6.1kg
Tyre: 8.8kg
Tot: 14.95

Compomotive CXR
Dim: 13x6J + 205/60/13
Rim: 4.5kg
Tyre: 8.7kg
Tot: 13.2kg

Compomotive CXR 6J
Dim: 13x5.5J + 185/60/13
Rim:4kg
Tyre: 7.9kg
Tot: 11.9kg

So going from 4x TD (@59.8kg) to 2x CXR 6 on the rear and 5.5 on the front (50.2kg) would save 9.6kg of unsprung weight!

loggyboy - 16/2/12 at 01:32 PM

But using the 185s reduces the gearing quite alot (circa 24mm diam difference) so the fairer comparison would be 7kg total.
Still a valid saving tho. Cheers for sharing.

EDIT - I wont delete, but just re-read yours to see the rears would be the same diameter so gearing would be unaffered

[Edited on 16/2/12 by loggyboy]

PAUL FISHER - 16/2/12 at 01:56 PM

Thats it, you go to all that trouble in buying super light rims, then fit R888's on them, the Avon cr500 or ACB10'S would be alot lighter option for the road and track, or if its just for the track get a set of slicks, even the AO48's are a bit lighter than the R888's, I think a cxr 13" with a 205 55 13 cr500 would only be around 9kgs.
Funnily enough Ive just changed my road wheels on the ARIES, gone from 185 60 14 on a 6" rim yokohama road tyre, to the same type of wheel but on a 5.5" rim, with a 185 60 14 A048, and they weigh 1kg per wheel more
I am going to get some pro race 1.2 13" with slicks for the track though

[Edited on 19/05/04 by PAUL FISHER]

loggyboy - 16/2/12 at 02:02 PM

quote:
Originally posted by PAUL FISHER
I am going to get some pro race 1.2 13" with slicks for the track though


Didnt think the proraces came smaller than 14"?

PAUL FISHER - 16/2/12 at 02:09 PM

Oh yes, they do now, Mac1 and MK and others have been selling them for a while now, 13" 7"


Car
Car

whitestu - 16/2/12 at 02:36 PM

quote:

But using the 185s reduces the gearing quite alot (circa 24mm diam difference) so the fairer comparison would be 7kg total.
Still a valid saving tho. Cheers for sharing.


Not sure about that in practice.

I have 185/60/13s on the front and 205/60/13s on the back. Compared to 195/55/15s [i.e standing one next to the other] the 185s are almost the same diamter as 195/50s and the 205s have a larger diameter.

I believe rolling radii can vary a lot from one make of tyre to another though.

Stu