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DU Gearbox - RPM Adjustment

Printed From: The Brick-yard
Category: T3 Section
Forum Name: T3 Wheel help
Forum Description: The most common question that pops up on these forums is what wheels fit and what do I need to get them on!
URL: http://www.brick-yard.co.uk/forum/forum_posts.asp?TID=91889
Printed Date: 06 Apr 20 at 15:46
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: DU Gearbox - RPM Adjustment
Posted By: bmouthboyo
Subject: DU Gearbox - RPM Adjustment
Date Posted: 14 Aug 16 at 11:54
I asked a similar question on club 80-90 but apparently here is where best to ask about wheels Tongue

I have a 1.8 Gti Engine (Mk1 Golf) with a DU 4 Speed gearbox in my Autosleeper and as I need new tyres all round wanted to see if I can replace my stock 14" steels with something that can lower my RPM. Not after anything fancy at the moment so decided my best bet firstly is to get some Mefro Steel Wheel - 6Jx16 ET30 5/112 Steels to replace my 14' steels.

I have put some data into a spreadsheet and this has allowed me to really compare the effects of various tyre sizes on my RPM's.

I wanted to check that my 'ideal' RPM' would be as close to the AAP box as possible? Or should I be looking more into my specific engines RPM / Torque curves?

Engine: VW Mk1 Gti 1.8 DX K-jet Engine
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Gearbox: 4 Speed: DU Code
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I tested a range of tyre widths and profiles and the ones which bought my RPM's to almost exactly the AAP box was:

205 75 R16 (Personal Favourite)
195 80 R16 (Closest RPM Match)
185 85 R16

So I have a bit of a choice. Wider tyres with less tyre wall or narrower tyres with higher tyre wall?

Will I foul the arches with this diameter wheel/tyre (Approx 718mm total)?

Cheers  :ok 

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