DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

All things round and their alignment to your direction of travel

Moderators: Moderators, User administrators

DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 22 Jul 2016, 12:01

OK so this will be a fairly detailed post as I want to be as clear and thorough as possible with this being such a complicated subject.

Background
I am currently restoring on somewhat of a budget a 1983 T25 campervan which had an engine conversion done many years ago by a previous owner. It has taken me a while to workout all its modifications from stock and am now trying to workout what size wheels / tyres would best suit its current setup.

It drives great but just wanted to check with the techies what would be the ideal wheel / tyre setup with my Engine and Gearbox as I will be needing to replace all 4 tyres next year. I am not looking to spend lots on the wheels and was hoping to go with the standard steel rims (5 x 112 pcd 5.5J x 14" ??) I have and possibly alter the type size if need be? However this is all a new area to me and I must admit I am not that clued up on this other than the basics. If it would really make a good difference I would consider after market rims, but nothing too expensive.

Engine: VW Mk1 Gti 1.8 DX K-jet Engine
Image

Gearbox: 4 Speed: DU Code
Image

Is it possible from this information to workout what tyre size would get the best out of my Engine / Box combo? Or is more info like Dyno readouts needed? Is it simply the final gear which can be altered?

Any advice? :ok
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 24 Jul 2016, 04:32

Is my goal to get the RPM for the speeds nearer to the Bright Green gear box codes? Will this be possible using the stock 14 inch steels?
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby marlinowner » 24 Jul 2016, 06:32

If you fit 205r80x14 instead of 185r80x14 that will give you a 5% increase in tyre diameter, which will drop your revs into the green range on the RJES chart.
1993 SA VW T25/T3 2.5i Microbus/homebrew camper
1981/1968 Marlin Kitcar TR6 Engine
User avatar
marlinowner
 
Posts: 1529
Joined: 28 Jan 2014, 12:02
Location: Scottish Borders
80-90 Mem No: 13646

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 24 Jul 2016, 10:31

marlinowner wrote:If you fit 205r80x14 instead of 185r80x14 that will give you a 5% increase in tyre diameter, which will drop your revs into the green range on the RJES chart.


Absolute legend thank you!

I am kind of reluctant to spend any money on alternative wheels at the moment as the money is better spent on the interior etc so being able to use my existing steels will be a huge help, but I was just unsure where to find information on the max tyre sizes I can use with them.

Is 205 80 x R14 the biggest I can go? And do you have any recommendations on decent tyres?

I see some sites dont list 205 80 R14, is 205 R14 the same? Not sure why not listing the wall ratio?

Thanks again :ok
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby marlinowner » 25 Jul 2016, 21:03

If the tyre profile isn't shown, it will be 80 (or 82).
You could possibly go to 215 width, but personally I would stick with 205.
There is some discussion of tyre choices in another current thread, I am running some Nokian AT 205/70r14 100 rated tyres at present, seem fine but not done many miles yet.
1993 SA VW T25/T3 2.5i Microbus/homebrew camper
1981/1968 Marlin Kitcar TR6 Engine
User avatar
marlinowner
 
Posts: 1529
Joined: 28 Jan 2014, 12:02
Location: Scottish Borders
80-90 Mem No: 13646

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 27 Jul 2016, 01:09

marlinowner wrote:If the tyre profile isn't shown, it will be 80 (or 82).
You could possibly go to 215 width, but personally I would stick with 205.
There is some discussion of tyre choices in another current thread, I am running some Nokian AT 205/70r14 100 rated tyres at present, seem fine but not done many miles yet.


I guess the downside to 205 80 R14 is heavier steering? Are there any others I should be concerned about?

The van is not lowered so should have any problems fouling arches etc.

Can anyone recommend a decent all weather tyre?

Cheers
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 27 Jul 2016, 01:11

marlinowner wrote:If the tyre profile isn't shown, it will be 80 (or 82).
You could possibly go to 215 width, but personally I would stick with 205.
There is some discussion of tyre choices in another current thread, I am running some Nokian AT 205/70r14 100 rated tyres at present, seem fine but not done many miles yet.


I guess the downside to 205 80 R14 is heavier steering? Are there any others I should be concerned about?

The van is not lowered so should have any problems fouling arches etc.

Can anyone recommend a decent all weather tyre?

Cheers
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 14 Aug 2016, 10:01

OK so 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.

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

I have decided my best bet firstly is to get some Mefro Steel Wheel - 6Jx16 ET30 5/112 Steels to replace my 14' steels.

Now 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?

I am a little unsure how the load rating works with tyres. Out of my options is one going to be easier to get the correct load rating for a heavy van like mine? (Autosleeper Trooper).

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

Cheers :ok

Image
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 21 Aug 2016, 07:45

Any ideas what would be preferred? 195 or 205
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby kit » 21 Aug 2016, 20:28

Just put them on the rear (either 205 or 215 the latter being more difficult to get) that way you don't alter your speedo reading or affect your steering.
1y Tin top rust collector.
kit
 
Posts: 2109
Joined: 17 Jan 2007, 21:01
Location: Southampton
80-90 Mem No: 4170

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 22 Aug 2016, 11:02

kit wrote:Just put them on the rear (either 205 or 215 the latter being more difficult to get) that way you don't alter your speedo reading or affect your steering.


What and keep the fronts on the 14Inch steels I have? Won't that look odd?
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby kit » 22 Aug 2016, 23:26

I kept the 14 inch on the rear and just increased the tyre size on the rear, you can see the difference but I don't think looks that odd.
1y Tin top rust collector.
kit
 
Posts: 2109
Joined: 17 Jan 2007, 21:01
Location: Southampton
80-90 Mem No: 4170

Re: DU Gearbox, Mk1 Gti Engine - What tyre/size wheels?

Postby bmouthboyo » 22 Oct 2016, 07:51

Sorry to keep dragging this thread back up but I thought better than starting a new one.

So I will be going with BG Goodrich All Terrain 215 70 R16 on the rear. I am not sure what to do with the front.

215 is the smallest width the All Terrain go it seems. Is there a way of calculating how much this will effect my speedo readings? And secondly will this make it difficult to steer?

Lastly can I just check that 215 70 R16 will actually fit front and rear?

Cheers guys
1983 Autosleeper Trooper - 1.8 Gti Conversion
User avatar
bmouthboyo
 
Posts: 407
Joined: 29 Apr 2009, 17:11
Location: Bournemouth
80-90 Mem No: 9396


Return to Wheels & Tyres

Who is online

Users browsing this forum: No registered users and 13 guests