Tires

[steveww]

Surely the 26r ran on wider than 155 tyres, thats why it had bigger wheel arches.

I think it really depends on what you use the car for. If you want originality and cruising around the local lanes than the standard widths are fine. If you are a bit more sporty and enjoy a track day here and there then some extra width should improve grip but at the loss of some finesse.

It is not so much the width that give the grip but the compound of the tyre and the softer compounds are generally only available on wider tyres. Also the smaller the aspect ratio the less the tyre rolls on the rim and presents a more stable footprint to the road.

Personally I would think that a 175x70x13 would give the best solution to a sporty driver, a bit more grip with some tyre roll so the fun is still there???

[terryrds]

I just came across an interesting possibility that some (US drivers) may be interested in, at www.coker.com - Michelin XAS 165HR13 . section=5.80, diam=23.2 classic rounded profile. From my experience with other cars, though, and agreeing with Steve's previous comment here, the classic Michelins seemed to have a hard compound- great for mileage, not for grip. price= $149 plus required tube $24.95 plus shipping - yikes! I think I'll keep looking for now. -Terry

[nuvolari]

In Europe there are no difficulties in obtaining modern 155r13 sized tyres. Tyre technology has moved on at such a pace that these tyres would have appreciably more grip (both wet and dry) than a 'performance' Dunlop SP Sport of 30 year's ago. However, by modern standards, they are very much economy tyres with fairly hard compounds and I understand Steve's desire to have more grip for track days etc.

Michelin do still make the XAS 165hr13 in the FF compound. This was used for the Formula France racing series in the late 60's and is a pretty soft compound. However the 23.2" diameter is likely to create some clearance issues on the Elan, although it would be perfect for the +2. Sadly, they no longer make the XAS or XAS FF in 155hr13.

Avon produce the CR6ZZ in 175x70hr13. This is a classic, rounded profile very soft compound tyre and is popular in classic rallying. However, they may spoil the feel of the car and again create clearance issues.

Another option I have discovered on the net are road legal competition rallying tyres. Maxsport make the RB4 tyre available in 165x70r13. This has a classic tread pattern and is available in a number of soft compounds. I would imagine that they would give very good grip, but have no idea on the rate of wear or suitability to the Elan. Maxsport tyres are quite cheap, and I know that a number of Elise owners use a Maxsport semi-slick (RB5?) for track days.

Hope this helps.

[steveww]

Just been to the Avon Racing tyres site and they do a 155R13 tyre in the CR6ZZ with a 157mm section. This should fit under standard arches on standard 4.5 rims. I am not at home at the moment but I will measure up the size of my 155x80x13 Dunlop SP10 and see how they compare. These Avons could be the answer for those who want more grip but do not want to mess with the car too much. B)

[nuvolari]

Steve - sorry to rain on your parade, but it's 155r15 not 13" on the Avon Racing website. The CR6ZZ would be perfect for the Elan if it was in the right size

[steveww]

Doh - you are of course right. I only had a quick squint at the site at lunch time when I was in the office. Still the 175x70x13 is a possibility. I have been told that this size will squeeze in, though I still need to do some more research on this.

[khamai]

Tubless tires are not problem on the steel wheels.

I'm currently running Bridgestone 165/65-13 RE92's. Only $40 from Tire Rack!

If anyone is interested the Panasport wheels, 13x5 are still available and subtantially stronger than OE steel wheels. Anyone thinking about autocrossing or track days needs these! Stock steel wheels are SURE to crack.

I was able to fit 175/70s on Panasports under an S4/Sprint Elan, but no chance with an S1/S2. Maybe on an S3.

For more info on the spec for the Panasport CL wheels check the GGLC website
www.gglotus.org and go to the "Tech" section and then to the Elan area.

One alternative is the Panasport wheel with the Yoko 032S (S=soft) 175/60-13. Shouldn't be a problem for S4/Sprint & maybe for S3. Fitting this combo on an S2 needs investigation (anyone?).

Kiyoshi

[terryrds]

Kiyoshi- Thanks for the ref. to gglotus- wealth of info there I had missed. Leads to more questions though.
What is the offset of the Panasport wheels? Your article says about 4", the drawing says 29 mm (huh? that must be for the thrust ring, or something else?)
Can you shed some light on why the section width of nominal 175/70/13 tires varies from 6.2 (Pirelli P3's) to 6.7 (Yok. Avid Touring) to 7.0 (Sumitomo HTR and most others in this size) ?
On my car ('65 S2), using my 13x5, 4" offset Minis, even a 6.2 section tire would hit the rear spring base unless I also used 1/2" spacers. Even with spacers a 7" section would hit.
I wonder if there's a difference in the outward projection of the hub mounting surface, between the knock-on and bolt-on cars (like mine)? If so, they would require different offsets. Or is there a difference in spring bases, between S2's and S3/4's? -Terry

[khamai]

<!--QuoteBegin-terryrds+Feb 3 2004, 02:19 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (terryrds @ Feb 3 2004, 02:19 PM)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin--> Kiyoshi- Thanks for the ref. to gglotus- wealth of info there I had missed. Leads to more questions though.
What is the offset of the Panasport wheels? Your article says about 4", the drawing says 29 mm (huh? that must be for the thrust ring, or something else?)
Can you shed some light on why the section width of nominal 175/70/13 tires varies from 6.2 (Pirelli P3's) to 6.7 (Yok. Avid Touring) to 7.0 (Sumitomo HTR and most others in this size) ?
On my car ('65 S2), using my 13x5, 4" offset Minis, even a 6.2 section tire would hit the rear spring base unless I also used 1/2" spacers. Even with spacers a 7" section would hit.
I wonder if there's a difference in the outward projection of the hub mounting surface, between the knock-on and bolt-on cars (like mine)? If so, they would require different offsets. Or is there a difference in spring bases, between S2's and S3/4's? -Terry [/quote]
Terry,
The offset on the Panasports is 29mm. The 4" number refers to the "backside" measurement - from inside rim edge to mounting face.

When measuring section widths of various tires one must also look at the "fitment width" of the wheel. The same tire on a 1/2" wider wheel typically is about 1/4" wider in section width. So, a 175/70-13 tire mounted on a 5 to 6 inch wheel will vary up to 1/2". Also consider that the rulers that tire companies use are made of "rubber"!

Finally there is a difference in the offset required for bolt-on vs knock-on for the Elan. Off the top of my head I don't recall, but I think it was in the neighborhood of 1/4-1/2" (knock-on requiring more offset or deeper backside). Thus a bolt-on wheel would only need a backside of about 3.5-3.75". Perhaps someone on the forum can measure them or I can check my stuff later (again I'm using fuzzy memory here on the bolt-on measurement).

Kiyoshi

[terryrds]

Kiyoshi- Ah! Of course! I forgot to allow for the rubber ruler factor! Actually, those sections were as measured by me on a 5" rim (P3's) or as indicated for 5" fitment on the Tire Rack site. One of the mysteries of life, I suppose.
I think I understand the difference between offset and backside now. Seems like varying thicknesses of different brands of wheel would make comparisons difficult (or maybe the thickness is standard?)
3.5", or maybe even 3.25" backside, sounds about right, given the neccessity for spacers I described above. But that might move the tire out into an unmodified fender. I'd be interested if any one could measure a bolt-on 5" wheel, Mini or Pana.
Thanks, -Terry

[steveww]

Now I am getting confused. The RD Enterprises site <a href='http://www.rdent.com/pages/parts.html' target='_blank'>http://www.rdent.com/pages/parts.html</a> lists the back space as 4" for KO and 3.9" for BO panasport. However the also state that the offsets are 28mm and 25mm Hmm when you consider that

Offset = Backspace - ( Rim Width / 2 )

and the wheel size is 5x13 the maths just do not add up. They also state that the max section is 165mm or 6.5"

I just measured the back space on my standard 4.5" steel KO as 105mm or 4.1" roughly. So it would appear that the back space of 4" is about right as any larger the wheel/tyre would hit the spring. You could go a bit smaller but run the risk of the tyre hitting the wheel arch.

You say you have 175X70X13 on 5X13 rims under standard S4/Sprint arches? Hmm they just might fit but tyre choice would be critical. You would need to keep an eye on the total section width, as this varies with different tyres depending on their construction.

[khamai]

Steve,

Just a minor arithmatical catch...

The wheel width is bead-to-bead. The backside measurement is from the inside edge (lip) of the wheel to the mounting face, thus the back side measure includes the thickness of the wheel lip from the bead to the outer edge. For most wheels this is about 1". In the case of a 13x5 Panasport wheel the lip to lip measurement is about 6" (154mm). 4" backside = 102mm. Lip to lip less the backside is 154-102=52mm, or about 26mm offset.

When I spec'd the design for Panasport I tried to pull the wheel in-ward as much as possible. Thus the backside is more than the expected 1/2" deeper than the stock KO wheel. (visit the GGLC site www.gglotus.org and go to the "Tech" section then to the "Elan" area for the spec given to Panasport).

At the time I spec'd the wheel the I owned an S4, so the spec was set-up with an S3, S4 or Sprint in mind. Now I've got an S1.5 (BO) & an S2 (KO), but have never tried the Panasports on the KO car.

Kiyoshi

[steveww]

You learn something new everyday. I did not know that the width is actually between the beads and not the actual total width. I guess it is obvious when you think about it as the tyre fits between the beads.

AFAIK panasport wheels are not available this side of the pond. However minilite www.minilite.co.uk will make up wheels to you given requirements. So it looks like I will be ordering some 5x13 KO with 4" of backspace and try to fit some 175x70 tyres under the arches of my S4.

[steveww]

There are a couple of articles on this subject in this months Club Lotus mag.

[type26owner]

Hi Kiyoshi,
Okay I'm arriving at your tire choice now that I understand what's really important with high speed tire dynamics. Missed this one while searching for suitable tires before because the aspect ratio was on the smallish side and therefore I didn't do a search for it by size. Please give me a full appraisal of the RE92s. The customer opinions given on the Tirerack are mostly from bozos as far as I can tell. The official testing done by TR indicates these tires aren't so bad on the racetrack. You on the otherhand I trust and greatly value your opinion. Have you had them on the track at 10/10s before? With the car stationary and shoving the car laterally with about 25lbs force how much sidewall deflection is there do you guesstimate? The Sumitomo's had about +/- ~1/2" and the P-Zero on my brothers Super7 had essentially none. I'd really like to drive onto the racetrack without having this uneasy feeling about my tires everytime.

What's the maximum air pressure that's printed on the sidewall? Their website doesn't give a value.

At least if there are any Geo's out on the racetrack I should be able to beat up on them using their OE tire. :rolleyes:
Thanks,
-Keith