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Increasing Rear Offset (numerically +38 To +45)

SLAPS
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SLAPS Rising Star

SLAPS

Posted
Posted (edited)

Hi All,

I have a set of jap rims which are:

F: 17x8" +38

R: 17x9" +38

The rims are surprisingly light; the fronts are slightly lighter than the std gtst rims where as the rears feel about the same.

The fronts sit nice with a 235 no scrubbing. The rears however with a 255 are an issue.

I've spoken to wheelworks who said a manufacturer 'typically' makes a larger cast and then machines down the hub slightly to achieve a given offset.

So.. heaps of meat on mine (looks like a built in spacer) I am looking at machining down the hubs slightly to say a +45 on the rear so I can run a wider rear tyre without scrub and excessive camber.

With the 17x9" +38 there's 14-15mm clearance between the wheel and the hicas tie rod end so plenty of room for a +45.

With a +45 on the rear the front and rear outer edge of the wheel will closer to being equal.

Compared to stock wheels.

17x8 +38 sit out +21mm

17x9 +38 sit out +34mm

Where as 17x9 +45 sit out +27mm.

Should I go more than +45 given there's still another few mm available?

As I am moving the rear wheels in closer to each other will it be less likely to under steer but possibly be a little more over steery?

Edited by TheRogue
toddlls Proficient

toddlls

Posted
Posted

I have 38 offsets on back with a 17x9 rim and 255 tyres were too wide even with flaring rear guards a little. Ended up going back to a 235 stetched to fit on rear which no tyre scrub now felt, arse-end little more slippery but meh-got it set up for skids anyhow.

Will be watching to see how you go here mate

SLAPS Rising Star

SLAPS

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  • Author
Posted (edited)

I'm hoping a 255, as much + offset I can squeeze, a rolled guard and a little little camber it will just fit. :S

In comparison to the std wheels the nuts screw on to the threads bugger all so fingers crossed there's plenty of meat.

Edited by TheRogue
SLAPS Rising Star

SLAPS

Posted
  • Author
Posted (edited)
there are much more effective ways to balance ur cars over/understeer than track changes.

The issue is I am trying to get as much semi-slick tyre under the rear as I can.

I doubt I'll be able to pull safely off any more than 2-3mm.

Either way these rims will do for now; I just don't like the idea of spending 1.5-2k on a set of rims when the car is only used for a little fun at the track and not driven on the street.

just get better tyres.

Not when your already at semi-slick level.

Edited by TheRogue
nisskid Grand Master

nisskid

Posted
Posted
The issue is I am trying to get as much semi-slick tyre under the rear as I can.

I doubt I'll be able to pull safely off any more than 2-3mm.

Either way these rims will do for now; I just don't like the idea of spending 1.5-2k on a set of rims when the car is only used for a little fun at the track and not driven on the street.

Not when your already at semi-slick level.

ok, then id be thinking less about track change, and more about clearance, what clearance issues are there on the inside?

also what gaurd modifications have u done if any?

SLAPS Rising Star

SLAPS

Posted
  • Author
Posted (edited)

I was simply curious how changing the rear track to improve clearance would neg affect handling if any. i.e rear track being less or more than front track etc..

Either way I spoke to the Troymeister; I will be fine with a 245 semi slick on the rear and rolled guards.

Semi's are apparently wider that the same sized road tyre so I shouldn't fit a 255 on the 9" rim as it will bulge a little too much.

Troy runs a 9.5" rear with rolled guards and no issues due to ride height.

I'm running 350mm with plenty of clearance so dare so I will be fine also.

Edited by TheRogue
nisskid Grand Master

nisskid

Posted
Posted

let me put it this way, the added tyre width will more than cancel out any tiny amount of oversteer bias u might have got from the track change. saying that, personally i would have just pulled ur guards out more.

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