Wheel and Tyre track setup

[sleepingperformance]

Castor can be adjusted thru a number of different ways, it just depends on how much people are willing to spend

[Grant@Honed]

I am running 16x8 / 15x7 (f/r) on my eg and honestly even tho it feels more direct than a 15x8 on the front, the 16in tyres have a slower compound than the 15in or 17in compounds.

That aside, I would not run a 17in front and 15in rear as the rear will be rolling around too much due to the extra height in the sidewall.

Also if you are looking at running a staggered set up, you do not want to run anything more than a 1.5in variance between front and rear widths.

For a DC5, we would most likely run a 18x10 front and 17 or 18x9 rear. We have found with the square set ups on lower speed tracks that they retain too much mechaical rear grip, causing the car to have a slight understeer tendancy. Good for a novice driver, but for those looking to get every last bit out of their set up, not so good.

On a DC2, to make 17x9's work, you will need to space the lower section of the front quarter panel, along with rolling and pulling of fhe front and rear guards. In turn, this will also require you to run a slightly higher ride height to allow for sufficent suspension travel

Side wall stiffness would certainly play into it. I wonder if you could counter the extra height with more stretch.

Thanks for that info on the panel work.

Reasons for being unbalanced (In my opinion anyways) would be It'll change your suspension geometry due to the physical high difference of the tyre+wheel combo. The front will be higher than the rear. Unless you compensate for it with the height of the suspension, then it will screw it up.
Also the difference in overall diameter and circumference between the two tyres really bugs me. I dont like the idea that they are spinning at different rates to each other and the wear on the brakes would be uneven and probably freak the ABS sensor.
However in saying that, i would do a 1 size difference in wheels, such as 18x10 front and 17x8 rear ONLY to fit a bigger tyre (295 possibly) on the front, in which i'll be looking to do in the future.

The tyre will hit on the inner guard since we can't adjust caster (unless you got special camber arms) to bring it forward.

You're right, the suspension geometry would have to be tailored for the set up. You would need to run longer than available front lower ball joint extension or similar.

You've brought up a good point about ABS. I think if I was running this theoretical staggered set up I would be using twin masters set up with no abs.

[sleepingperformance]

The 17in front 15 in rear idea is not worth the hassle. Have been weighing it up for a while myself and seeing the difference in compounds, along with a few other certain things has made me move away from it.

You also need to look at top tier motorsport. There is a reason why no one runs a 2in diameter difference. JGTC run a 1in difference in diameter, some FF time attack cars do, but thats about it

[Grant@Honed]

Does the actual compound of the rubber change between 15" and 17" tyres? Take Advan AD048 for example.

[sleepingperformance]

A048 is a compound that isnt really used anymore. A050 medium has become the norm for most CAMS controlled events.

Even tho Advan, Hankook etc say their compounds are the same, we have seen IPRA testing results that physically prove otherwise. 15, 16 & 17in tyres were tested. 16in was the slowest, 15in was 1 sec quicker and 17in another 0.5-1 seconder quicker than 15in

[Nathannnnn]

Thanks for the info guys! My car's all bolt ons and the main track I'll be on is winton. I'm leaning towards the square setup for tyre rotational purpose.

I know a usual staggered setup there isn't too much of a difference in track width (e.g., 8+35, 9+35). But would the track width between a 8 +35 and 9 +22 be enough to make the car more prone to oversteer than say an 8+35, 9+35 setup?

[Grant@Honed]

Sorry for hijacking your thread!

Stock track on a Dc5 is 1490mm.

Stock wheel on a DC5r is a 17 x 7 +60

Wheelbase: 2570mm

Stock wheelbase/track ratio is a pretty narrow 1.7

It is commonly accepted that wheelbase/track ratios between 1.55-1.7 are desirable for circuit racing

With the 9 +22 on the front your new front track will be: 1566mm

This gives a wheelbase/track ratio of : 1.64

With the 8 +35 on the rear the new rear track will be: 1540mm

wheelbase/track ratio: 1.66

So the front track is only 1.7% wider than the rear. IMO a wider front track is what you want and 1.7% is definitely not excessive.

This would be a pretty extreme set up in terms of body work. The front wheels would be approximately 63 mm wider a side!

[Nathannnnn]

That's the stock wheel for for the JDM DC5R. The Audm one is 16x6.5 +45, and the hubs are different. But great info and thanks for the help!

[Grant@Honed]

That's the stock wheel for for the JDM DC5R. The Audm one is 16x6.5 +45, and the hubs are different. But great info and thanks for the help!

Ah ok! I wasn't sure on that but you get the idea. No worries!

[ChargeR]

To the OP, run the same width front and rear. Assuming you don't have heaps of experience (is this true?) then you'll gain more from having consistent tyres and thus be able to develop as a driver than you will by bolting a fancy staggered setup on. This is speaking from experience.

Not sure if its a typo with the 15x7 but it definitely wouldn't be suitable. The overall wheel size difference will make the car unbalanced and extremely tail happy

I don't fully agree with this, like anything in cars there's more than one way to skin a cat/make a car handle. The challenge with a 15" with a rear wheel will be as you say the effect of the different rolling diameters/ride height on suspension geometry. The physical sidewall height of the most popular performance 15 and 17" tyres is basically the same ie. 225/45R15 and 245/40R17 have approximately the same sidewall height, so I wouldn't expect markedly different response from the tyre.

I am running 16x8 / 15x7 (f/r) on my eg and honestly even tho it feels more direct than a 15x8 on the front, the 16in tyres have a slower compound than the 15in or 17in compounds.

That aside, I would not run a 17in front and 15in rear as the rear will be rolling around too much due to the extra height in the sidewall.

Also if you are looking at running a staggered set up, you do not want to run anything more than a 1.5in variance between front and rear widths.

For a DC5, we would most likely run a 18x10 front and 17 or 18x9 rear. We have found with the square set ups on lower speed tracks that they retain too much mechaical rear grip, causing the car to have a slight understeer tendancy. Good for a novice driver, but for those looking to get every last bit out of their set up, not so good.

On a DC2, to make 17x9's work, you will need to space the lower section of the front quarter panel, along with rolling and pulling of fhe front and rear guards. In turn, this will also require you to run a slightly higher ride height to allow for sufficent suspension travel

As noted above, with a 15/17 stagger setup most likely the sidewall height will be pretty much the same given the limited tyre sizes available. I don't agree with arbitrarily stating that 1.5" of wheel width difference is the most recommended, what have you based this on? I personally have used 1 and 1.5" and recommended 2" to others with excellent results, ie. Mugsee runs 11/9 and has had excellent results, 1:37s at Winton, in what is essentially a streetable full weight DC5R (albeit with a 2.4) with basic bolt ons and some suspension tweaks.

I wouldn't hesitate to run more differential between front and rear wheels if the car is developed as a package around those tyre sizes. I'd like to trial anywhere between 1" and 3" of wheel width stagger, with appropriate tyre sizes, and I can tell you right now without testing that the 1" wider fronts will be slower than the rest.

[Nathannnnn]

That is correct. ChargeR knows best

[RA73DR]

hey guys,
hoping i can get a bit of advice please.
i bought a set of rega evos for my dc5r. 17x9 38 for front and 17x8 35 for back. i have my guards rolled and will be fitting buddyclub rsd coilovers.
i am planning to run hankook rs3 tyres all round, thinking 235/45 at the back and i would like to run 245/40 at the front.

would i have any issues with this tyre set up ?
i am building the car to be my daily car that i take t the tack as often as i can so i dont want to be hassled by police too much in terms of width of wheels kind of worried that 245 at front might poke out too much ?

the car isnt stock it is making 161 at the front wheels.

any input is appreciated, thank you

[Nathannnnn]

hey guys,
hoping i can get a bit of advice please.
i bought a set of rega evos for my dc5r. 17x9 38 for front and 17x8 35 for back. i have my guards rolled and will be fitting buddyclub rsd coilovers.
i am planning to run hankook rs3 tyres all round, thinking 235/45 at the back and i would like to run 245/40 at the front.

would i have any issues with this tyre set up ?
i am building the car to be my daily car that i take t the tack as often as i can so i dont want to be hassled by police too much in terms of width of wheels kind of worried that 245 at front might poke out too much ?

the car isnt stock it is making 161 at the front wheels.

any input is appreciated, thank you

I ran those exact wheel and tyre specs. You'll be fine

[RA73DR]

thank you !any scrubbing issue on the inside tho ? i dont plan to be slammed i want that functional set up and from what i hear the guards slightly higher than the tyre like couple finger gap is the way to go ?
ill be getting jdmyard to fit em so i guess they can do it according to my needs

[stienerv2]

I have a 17x9+35 and 17x8+35 with 245/40 fronts and 225/35 rears and about 1 finger gap all round with barely any scrubbing issues. I hear a slight rub when i turn my steering wheel on speedbumps.

I used to run 2 finger gap and had no rubbing issues at all. The DC5 should be an easier car to fit than my EP anyways.