16" Wheels on a 2500M

[tvr43]

I was wondering if anybody might have any experience running 16" wheels on an M. I have a '74 2500M and it's been practically impossible to find any decent 195/70 R14 tires in the US.

I have been looking at switching out to 16" wheels for a few years, but I think I'm finally going to take the plunge because I'm getting to the point where I really need to replace my tires. (Uprated hubs/wishbones/bushes/springs & dampers are planned to follow hopefully this winter)

Ideally, I would like to run the following:
FR: 205/55 R16 on 16x7
RR: 225/50 R16 on 16x8

I'm looking at this tire size split because it was what was run on the 2000-2003 Honda S2000 in the US which means there is a huge selection available and probably will be for a long time into the future.

Has anyone run anything like this before? Any ideas what wheel offset might we required?

Any help/insight/guidance would be much appreciated.

-John

[Slow M]

What type of "uprated" parts will you be using?
Why?
Who will supply the wheels?

I think with 16s you have enough clearance that you can change the offset to move some tire to the inside a bit. It'll increase the turning radius because you'll start rubbing on bits and have to put a bigger stop (limiter) in.

I just read something in this forum, maybe 2-3 years back where 16s were discussed. Can't remember detail too well though.

Too bad the search function is fubar.

B

[tvr43]

I also remember stumbling across that 16" wheel discussion topic from a few years ago at one point but I couldn't find it when I was looking again.

As for wheels, I've been thinking about the Panasports barring coming across anything better. The Bornemann cosworth TVR runs them and has a nice clean, classic appearance.
http://www.bornemann-fahrzeugtechnik.de/78.html

I think I remember somewhere that the Bornemann car ran 16x7.5 with a -16mm offset but I couldn't find the posting.

As for the other parts. I'm looking at Adrian Venn's 1-piece FR wishbones and reinforced RR wishbones + bushings, the racetorations or southwick FR hubs, with RR hubs TBD. The goal is to build a solid, durable foundation for the modern rubber and increased power to come in the next 18 months.

[Slow M]

Slow M said:

Why?

tvr43 said:

...The goal is...increased power...

Er, how do I tell him that I was fishing for how he was planning to do this and what result he was looking for?

You could contact Fabian.
http://www.pistonheads.com/gassing/profile.asp?mem... He probably has the widths and the offsets recorded on his TUV (sorry, no umlaut on my keyboard) papers.

B

[tvr43]

Slow M said:

Slow M said:

Why?

tvr43 said:

...The goal is...increased power...

Er, how do I tell him that I was fishing for how he was planning to do this and what result he was looking for?

Street use mainly with plans to do an occasional track-day or autocross. Basically a quick, fun backroads car. I've owned the car for 12 years now and have been wanting to get some more out of it for a while but finally have some funds to do it.

As for the power, I'm going to keep the TR6 motor rather than swapping out to something different. Aiming for 190-200hp or just north which should be doable using all the standard TR6 tuning bits. Dropping in a SBF or one of the other traditional swaps is quite tempting but I'm looking to keep the original character of the car.

[Slow M]

I was going to do this before I lost my marbles.
There were a few people whom you really should talk to about your engine.
I wish I could remember all their names but only Glen Effinger and Richard Good come to mind.
I'l post if I remember.

BTW, planning/have an O/D?

B

Edited by Slow M on Saturday 10th April 20:41

[DavidY]

Yes you can run 16" rims on an M, but you are going to run into problems with your chosen tyre sizes (I ran those tyre sizes on 15" rims and the rear tyres would kiss the wheel arch on full suspension travel. You will also have to consider reducing the mount of steering lock to stop the front wheel/tyre kissing a wishbone on full lock.

Bigger rims work well on an S as they have larger rear wheel arches but on an M/Taimar care should be taken unless you intyend to modify the rear arches. Unless your car has a very trick motor, I would consider running 205/45s all round on 16 inch rims.

Adrian Venn is really the man to speak to on this as he has lots of experience in this arena

davidy

[tvr43]

Slow M said:

BTW, planning/have an O/D?

Either an O/D or there's a new T5 conversion for TR6/TVR:
http://www.dupontmachining.com/

The kit seems well engineered, and I've heard good things. The owner of the company has been very helpful/informative with any questions I've asked.

I'd use either a 4.1 or 4.3 diff given how tall of an 5th gear the T5s run.

DavidY said:

Unless your car has a very trick motor, I would consider running 205/45s all round on 16 inch rims.

I'd be OK with 205s all-around but my preference would be to keep the 55 aspect ratio if possible to maintain ride height (I already drag exhaust more frequently than I'd like) and keep the correct tire OD.

[DavidY]

205s all round would mean that you could run a 7" rear, which will gve you less cearance issues than an 8" rim with 225s (and thats from someone who ran 9" rims!!) It also gives the advantage that all wheels/tyres are the same (assuming offsets are the same - bolt thru spacers at the front?)

davidy

[Slow M]

tvr43 said:

Either an O/D or there's a new T5 conversion for TR6/TVR:
http://www.dupontmachining.com/

The kit seems well engineered, and I've heard good things. The owner of the company has been very helpful/informative with any questions I've asked.

I'd use either a 4.1 or 4.3 diff given how tall of an 5th gear the T5s run.

Check weights. My 4-speed w/ "A"type O/D was WAAAYYY heavy.

What type of T5? Is it feasible to do a CR 5th and leave the 3.45 diff gear? You'd probably still would want a LSD.

(Sorry abt grammar, still half asleep.)

B

[DavidY]

Although the T5 is strong, it has a very slow shift, this is something to bear in mind, if you wnat to use the car for competition use, you may find it a bit slow

davidy

[tvr43]

DavidY said:

Although the T5 is strong, it has a very slow shift, this is something to bear in mind, if you wnat to use the car for competition use, you may find it a bit slow

davidy

Thanks for the input, that's a good point to check before going forward. I'm not 100% set on that route, it just seemed like a good option with some potential.

I had been looking at this trans which was supposedly the final/best iteration with the best synchros and short-throw shifter:
http://www.fordracingparts.com/parts/part_details....

Slow M said:

Check weights. My 4-speed w/ "A"type O/D was WAAAYYY heavy.

Supposedly the fully assembled T5 is approx 5lbs lighter than the TR6 4spd w/ O/D.

[pumpkin]

I cannot bring up the old thread about this so here is some of the same info. I run 16 X 7 Pannasport with 6mm +ve offset on my 5000M. I use 3mm spacers on the front and run 205/55-16 tyres all round. At the front on full lock the rims touched on (I think) the trunnion bolt, nut and flange and a small amount of grinding was necessary once all the alignment was correct. The bit of the wheel that was rubbing was the horizontal to vertical corner of the wheel well (if that makes any sense to anyone) A larger diameter wheel would not have this problem. Also at the front, depending upon the actual tyre geometry and how the bonnet is fitted I got some rubbing of the bonnet lip over the wheel. Again a small amount of grinding sorted this out but re adjustment of the bonnet would also have done it.
I have heard that 7" zero offset wheels work. These would stick out only 1/8th extra at the front and I could have coped with this. It would have reduced rubbing of the rim. Although I use 205 section tyres all round so I can move tyres between front and back I think I could fit 215's at the rear with the extra 1/4" obtained from the +ve offset. I have been through several different tyres on the car and the shoulder shape makes a lot of difference. The tyres that rubbed at the front were Kumo Extas and there was no rubbing with Bridgestone RE01R's. Since then I have changed my bonnet and seem to have more clearance.
16" wheels seem like a good compromise for the car. The tires are fat enough to look almost right but low enough profile so that some high performance tyres are available. It taimede the car and stopped me getting the wheelspin in third in the dry which my old high profile "Mr Wiggly" tyres produced.

[tvr43]

pumpkin said:

16" wheels seem like a good compromise for the car. The tires are fat enough to look almost right but low enough profile so that some high performance tyres are available.

My thoughts exactly.