Wheels/tyres

[Simonpfhc]

Hi all,

Before I start, I want to clarify that this is not a post to discuss the best size of wheels or tyres, just some feedback that may help others.

After lengthy consideration, I have decided to fit 6x15 triple-laced, competition wire wheels from MWS and 205/70x15 Pirelli Cinturato tyres. I still have the original chrome 5x15 wire wheels fitted with 185/70x15 Michelins. So I took some measuremts that some of you may find useful to help with your decisions.

Also, after making direct comparisons side-by-side, I chose full stainless wire wheels instead of chromed ones. They are slightly more 'yellowy' than chromed ones, but unless you have them next to a chromed set, you can't really tell, and on the car you wouldn't really know they weren't chrome. I chose them as I plan to keep the car and they will hopefully last longer than chromed ones. However, one aspect that I was completely unaware of was how significantly lighter they were compared to the same size in chrome! All the additional plating seems to add considerable weight.

Ok, so the measurements compared to the standard set:

Weight of new wheel/tyre combo = 19.9kg
Weight of old wheel/tyre combo = 20.8kg

So the larger stainless wheels with larger tyres are lighter than the smaller originals!

Width of tyre mounted on wheel-

New = 211mm
Old = 186mm

Nothing too surprising there. I have found that tyre widths vary greatly between different manufactures even though they are listed at the same size.

Circumference of tyre mounted on wheel at 30psi

New = 213.2cm
Old = 214cm

As expected, the newer tyres have a slightly less rolling radius, but not too bad.

The fitment on the front presents no problems. The general concern centres on the rear fitment. MWS publish all the dimensions of their wheels on their website, and as per the specifications of the 6x15 I purchased, I can confirm that pretty much all the extra width is on the outside of the wheel. I had already removed the rear bump stops with the expectation of them fouling the wider setup, however they do fit (almost!). Due to the tolerances of the IRS assembly, mine is a few mm off-centre. The nearside bump stop will need about 1 or 2mm ground off to allow clearance. The off-side fits without any clearance problems.

Unfortunately I won't be able to experience how the wider setup feels to drive as the car won't be ready until spring (or later....) but I'm not expecting anything particularly horrible:-)

Hopefully this is of use to others.

Cheers

[PeterCrespin]

Always good to have hard data, thanks. Comments, sight unseen:

Standard comp triple-laced is 5.5" rim, so some the fitting issues should disappear.
I don't believe plating (measured in microns) is responsible for any easily-identifiable weight difference. Hub spoke and rim sections and lace pattern would be my candidates.

Do you have weights for wheels alone and tyres alone? Combined weights cloud the issue, although in practice would mostly be all that matters.

Didn't understsnd the bump stop grinding comment if you said the extra width was on the outboard side? Presumably there is already clearsnce and you wish to add 1-2 mm extra, (because that would be insufficient clearance on its own)?

[Gfhug]

Simon, have you kept the old wheels? For it'll be interesting for you to do back to back tests of your new versus old wheels and give feedback.

Yes, it has been aired many times the preferences for and against the wider wheels/tyres. I recently went from 205/70 15 Michelins on standard 5 inch wires to 185R15 Vredestein and feel so much happier with the car.
But I'll be genuinely interested to read what you feel and hope you like the set up you've gone for.

Geoff

PS Stand by for lots of opinions

[Simonpfhc]

Hi Peter,

The weight difference was surprising. It was immediately obvious when I was at MWS - they showed me identical sized/laced wheels. The full stainless one was significantly lighter than the chromed one. I can't say for sure where the weight difference lies, but just presumed it was the plating.
The fitting comments I made regarding the bump stop arise from the wider section tyre. So despite the actual wheel not presenting a fit problem, the tyre can.

@Geoff, I do still have the original wheels and tyres. A back-to-back test would indeed be interesting, but the Michelins that are mounted on the old wheels are over 20 years old so I really don't to be using them at all :-(

I also plan to see if the new wheel/tyre will fit into spare wheel recess - will report back.......

Cheers.

[mark10337]

I was over at MWS also yesterday! Collected 2 original curly hub wheels, one needs a new rim and both 72 new spokes and nipples each.
Also 4 easy clean flat hubs that needed 72 new spokes and nipples each. There has to be a cheaper way of replacing them.

[christopher storey]

I cannot understand how the new tyres are effectively the same rolling diameter as the old ones if, as you state, they were actually 185/70s. Are you sure you are not mistaking them for old standard profile 185 which were roughly 185/80, and thus about 9mm greater diameter than the 205/70 ?

[alfazagato]

I cheated somewhat and retained the 185 tyres on 6" rims which both fit the arch better visually and clear the bump stop. However, as to the relative weights I am very surprised as the triple laced rims have more metal content even assuming that the hubs are the same. Can it be that the "old fashioned" 185 tyres are a heavier construction (greater depth of sidewall x 2) than their modern wider counterparts?

[Gfhug]

For comparison: my old 5" wires with new Vredesteins 185R15 weigh in at 19.9 kg, the same as Simon's new 6" with 205/70 15s.

Geoff

PS, come on David, tell us how heavy (=light) your Borranis are

[Simonpfhc]

I've now checked the fitment in the spare wheel well and can confirm that my 6" rims with 205 tyres do indeed fit - just!

@Christopher - I have double checked and you are right, the original tyres are 185R15 and not 185/70x15.

Cheers.

[Hugo]

Are the stainless wheels the same gauge metal as the mild steel ones? Stainless is stronger so they may be thinner?