Scrub Radius vs Offset

I'm looking at fitting some Astra-H rims to my Astra-G track car.
The offsets are smaller (ET37 vs ET49) therefore this should increase the track by 24mm so should improve turn-in & grip.
I also found that the OEM scrub radius is approx. -5mm, so fitting the ET37 wheels will result in a positive scrub radius of +7mm.
I've researched a bit about the affects of positive scrub on FWD and the effects don't look too encouraging, however as it's only going to be used on track I'm sitting on the fence on going for it.

Q. There must be a lot of you guys running aftermarket rims with positive scrub (lower ET than 42), how are you finding them, esp. on track?

im running et37 on the front to miss the brakes and it just catches the plastic arch liner 30-40mm lower with factory camber setting

got et41 on the rear now with no issues also running vectra vxr rear discs and white line camber shims that space it out some
with et37 on the rear they scub the wheel arch and rear bumper mount

Cool, Shouldn't have a problem with clearances as the rims will be 6.5j X 16, 205/50 tyres.
Mainly I was looking at finding out real world effects on handling, tramlining, steering kickback etc
E.g is all ok when the near side tyre goes through a puddle? How does the steering load up in bends? Stability under braking? Etc etc cheers

Project L850 said:

Cool, Shouldn't have a problem with clearances as the rims will be 6.5j X 16, 205/50 tyres.
Mainly I was looking at finding out real world effects on handling, tramlining, steering kickback etc
E.g is all ok when the near side tyre goes through a puddle? How does the steering load up in bends? Stability under braking? Etc etc cheers

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all fine ""quafe diff""

I've ran various wheels on my track car all with varying et's and widths I found the astra mk4 deals with scrub radius just fine. I did find a noticeable difference using lighter weight wheels, the best ones vauxhall did in a 16" was the vectra b supertourer they were 1.8kgs lighter per wheel than my other vauxhall wheels

dewismotorsport said:

I did find a noticeable difference using lighter weight wheels, the best ones vauxhall did in a 16" was the vectra b supertourer they were 1.8kgs lighter per wheel than my other vauxhall wheels

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What is the exact weight of that?

dewismotorsport said:

I've ran various wheels on my track car all with varying et's and widths I found the astra mk4 deals with scrub radius just fine. I did find a noticeable difference using lighter weight wheels, the best ones vauxhall did in a 16" was the vectra b supertourer they were 1.8kgs lighter per wheel than my other vauxhall wheels

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Cheers Dewis I'll give the Astra-H wheels a go, bought a set on the bay for £70 so well worth a punt.

Vectra-B use ET44 wheels. If you fit these without spacers to an Astra-G they will give 0 scrub radius - this is a big no no for handling as you'll get tyre squirm!! Worth considering for the future with some spacers though. Standard Astra-G 16" wheel mass (no tyre) is 9.8 - 10.0 Kg depending on the design, can't find any mass info for the super touring wheels, guess they were engineered by MSD. Would be good if you know the actual weight?

I currently have team dynamics pro race 1.2 in a 18x8 et 37. The vectra wheels work well with the spacers as the arches are fairly big on the astra g.

I have one with no tyre on so will weigh it tomorrow and let you know. They will be for sale at a later date if there any use to you.

TD pro's are a fine looking rim, what tyres are you using?
I've just got a set of Dunlop CR311's to try on the Astra-H rims - hopefully another step up from the very worn Toyo R1R's which did a fine job.

I'll be interested in the supertouring wheels you've got.

I've got two sets one for wets Toyo T1R and the drys which are Dunlop direzza 03g

They super touring rim weighs 7.5kg each with centre cap.

I'll let you know when there up.for sale, can come with tyres uniroyal rainsport 2 or without

TD pro race 1.2 @ 16x7j = 7.4kg, surprised the super touring are that close!!! Now very interested.

dewismotorsport said:

I've got two sets one for wets Toyo T1R and the drys which are Dunlop direzza 03g

They super touring rim weighs 7.5kg each with centre cap.

I'll let you know when there up.for sale, can come with tyres uniroyal rainsport 2 or without

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Just bought some Intra SuperTouring rims and according to my scales they are 8.4Kg. Not as light as I hoped

Weird, I weighed mine on a set of calibrated postal scales. I will check again when I'm back at work

dewismotorsport said:

I've ran various wheels on my track car ... ... I did find a noticeable difference using lighter weight wheels ...

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The lighter the wheels, the lower the rotational inertia (= better acceleration and braking) and the lower the unsprung weight (= better handling).

Hence why really serious wheels are made from magnesium.