Thread: Wheels Offsets
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Old 05-30-2006, 07:15 PM
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400TT 400TT is offline
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Churchy, not sure if you are quite following my rims sizes.

Your 8" & 10" rims are measured at the tyre bead. So measured on the inside edges of the rim.

If you measured your 8" rim from edge to edge, it would actually measure 9"
Same with your 10" rim, it would measure 11".

Since front space & back space are measured from outside edge of rim, you need to calculate this using 9" & 11" rim measurements.

This is why wheel manufacturers use offset, it's measured from wheel centre line to bolt up face. Don't have to worry about true width of rim.

Hooray, sounds like Simmons have true 18" rims now. Next time I'm near some 17" Simmons I'll measure the centre. I might have to put Simmons back on my shopping list. I checked 12 months ago and they were definitely only 17" centres and the only 18" Simmons I saw had 17" centres. Glad that's fixed. Maybe they offer better rim to centre offsets as well.

With those size brakes you won't have any problems with true 18" wheels. 17" wheels would be close.

For everyone elses benefit. one of the clearances I was actually talking about is if the caliper sticks out proud of the the bolt up face. Those pesky centre-rim bolts can cause fouling in that case if the wheels are small enough.

From memory my front brakes are just over 400mm in diameter - 355mm x 36mm. The problem is the 6 piston calipers that really stick up proud of the bolt up face and cause clearance problems with centre.
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Last edited by 400TT; 05-30-2006 at 07:21 PM..
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