Lotus Elan

Tire issues

PostPost by: Jon Eckman » Fri Apr 25, 2008 4:59 pm

Last night I replaced the Dunlop SP20 155R13 78S front tires on my
stock 66 S3 with a set of Vredstein Sprint T80 155R13 78T's, which I
had seen recommended by some here in the past. On the driver's side
(LHD) I could move my fingers, with a little play, between the top of
the tire and the body, but on the passenger side there was not enough
clearance to move my fingers through. Both front shocks and springs
were recently replaced. I don't remember this condition with the
Dunlops. Any ideas about what might be going on here?
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PostPost by: 1964 S1 » Sat Apr 26, 2008 1:33 am

Hello Jon,
Do you still have your old tires? If you could remount them you'll find the same differences in tire to body clearances but the old tires gave more room all around.
I'll speculate the minimal clearances reflected between the old and new tires are caused by the body mounting on the chassis. They are seldom straight.
You're talking fractions of an inch here and the body to chassis mountings were never identical due to fiberglass/bobbin and folded chassis construction. Shims between your body and chassis are one solution choice.
Eric
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PostPost by: chicagojeff » Sat Apr 26, 2008 1:43 am

I think Eric is spot-on. By the way, fellow Yanks, what are we gonna do about no more Bridgestone Potenza RE92s available? I have the stock wheels on a Baby Elan, well, actually I also have the Panasports, but who else makes something that will fit?
Jeff in Finally Thawed Out Chicago
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PostPost by: archigator » Sat Apr 26, 2008 2:36 am

I have Kumho Power Star 758's on my Sprint. 155/80 R-13. For non-racing applications, they seem to work fine... and they're quite inexpensive.

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PostPost by: Chrisrich » Sat Apr 26, 2008 2:36 am

Jon, I have the EXACT same problem with the EXACT same tires!
Yesterday I took a ride out to see my friend's elan to take measurements and compare sizes. He has an older set of pirelli P200 tires in a 155/70 size that are a good 1" smaller than the one's you and I have and he has tons of clearance.

Only difference for ME is that I got the car last summer with an worn set of 155/80 tires that had worn through the inside of the passenger wheel well. I replaced all shocks/dampers and hoped the problem would go away, but still have almost zero clearance on the passenger side (can barely put my fingers in there). I threw a set of the Vredensteins (or whatever they're called), same one you have.

I bought ANOTHER pair of V's, but this time in a 145/74 spec, which is 1/2" smaller (which should give 1/4" more clearance, I guess) and I'm waiting to have them mounted and balanced. I can't find anything smaller. Tried Universal, Coker, Tire Rack.....

As it is now, I can't ride with anyone in the passenger seat, as I touch the wheel on some corners. I can let you know how the 145s do.....

Chris
1970 Elan S4 DHC 45/9780 1972 Triumph TR6
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PostPost by: 1964 S1 » Sat Apr 26, 2008 3:03 am

Hi Chris,
Smaller tires aren't the answer, back then even Lotus had factory spec tolerances. Either your chassis is flexing due to damage or the suspension needs rehab.
Front tire clearances are close on the Elan but most of us drive around very fast on bumpy roads without a problem.

Eric
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PostPost by: RotoFlexible » Mon Apr 28, 2008 1:33 pm

I had my S2 with its new Vredestein Sprint+ 155/13's out chasing Elises and Exiges around back roads on Sunday, with a passenger (actually, I was the passenger much of the time). We noticed what sounded like very light tire rub in the rear in hard corners, especially with a slight bump. The fronts can catch the lip of the wheelwell when they are significantly turned, as in parking, but there didn't seem to be a problem when underway. I have to have a look underneath for the contact spots. I didn't have these problems with my previous set of Michelin Rain Force 155/13's, so the Vredesteins must be slightly larger.

It's also possible that the rear hubs are a little farther out than before. I replaced the original shafts and hubs (which were well worn) with TTR steel items.

Apart from the rub issues, which I believe are minor, the tires are excellent. Good grip and no unpleasant surprises.
Andrew Bodge
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PostPost by: denicholls2 » Tue Apr 29, 2008 2:33 pm

The tires aren't the size you think they are?

Listed tire sizes are confusing for older spec tires. 155/75/13's aren't original.

Neither are 155/85/13's.

The original size is 155/13. I think the actual aspect ratio was around 80, and that's what the Tire Rack site returns whan 155/none/13 is chosen

I would not put a 145 tire on a Lotus. That's one step more silly to me than putting a wider tire on "just because it looks cool." The car was designed to work well with the original spec tires, and I can attest that indeed it does. I can also attest that clearance is marginal even with the right tire, but should be adequate.
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PostPost by: rcraven » Tue Nov 15, 2011 1:45 pm

Wasn't the original tyre size on the S3 145 x 13, not 155 x 13 ?
Robert
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PostPost by: Orsom Weels » Tue Nov 15, 2011 5:39 pm

rcraven wrote:Wasn't the original tyre size on the S3 145 x 13, not 155 x 13 ?


That's what I had always beleived, indeed, is that not why the arches are more squared off & flared on the S4, to accomodate the 155x13 tyre ?

Regards, Tim
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PostPost by: Galwaylotus » Tue Nov 15, 2011 7:14 pm

. . . is the right answer! :wink:
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PostPost by: ftsoft » Tue Nov 15, 2011 10:17 pm

Yes, the original tire size was 145x13. I'm surprised that I can still remember, as I have run 155's for a long time, but I bought my car new with Dunlop SP 41 145x13's.

Frank
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PostPost by: nebogipfel » Wed Nov 16, 2011 2:06 pm

Galwaylotus wrote:. . . is the right answer! :wink:


Indeed it is. :wink:

This tired (geddit :D ) old topic comes up from time to time and clearly if the shell is perfectly symmetrical on the chassis you may get away with 155's on an S3 or older and the same can be said of wider tyres on a S4.

Surely the sensible and obvious answer is to fit the correct size tyres, then there is no issue (unless the shell is really badly fitted).

The tiny increase in tyre width is going to make bugger all difference in your ability to drive along twisty roads, so why create a problem where there aint one?

Just my two penneth as usual :D
John

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PostPost by: billwill » Wed Nov 16, 2011 3:58 pm

nebogipfel wrote:
Galwaylotus wrote:. . . is the right answer! :wink:


Indeed it is. :wink:

This tired (geddit :D ) old topic comes up from time to time and clearly if the shell is perfectly symmetrical on the chassis you may get away with 155's on an S3 or older and the same can be said of wider tyres on a S4.

Surely the sensible and obvious answer is to fit the correct size tyres, then there is no issue (unless the shell is really badly fitted).

The tiny increase in tyre width is going to make bugger all difference in your ability to drive along twisty roads, so why create a problem where there aint one?

Just my two penneth as usual :D


Nay!

The clearance on 145 tyres on an S3 is very small on both sides, indicating that the bodyshell is centralised, but 155 tyres do rub slightly on the shell on normal circumstances & may rub more when hot or partially deflated etc. 155 tyres also aggravate the probability of the front wheel catching on the S3 arch if the suspension is down on a slight corner.

Hence my Elan S3 was fitted with S4 wheel arches at the rear as well as the S4 nose & arches on my first prang (when I had owned it only a year in 1970ish).
Bill Williams

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PostPost by: nebogipfel » Wed Nov 16, 2011 4:50 pm

billwill wrote:
nebogipfel wrote:
Galwaylotus wrote:. . . is the right answer! :wink:


Indeed it is. :wink:

This tired (geddit :D ) old topic comes up from time to time and clearly if the shell is perfectly symmetrical on the chassis you may get away with 155's on an S3 or older and the same can be said of wider tyres on a S4.

Surely the sensible and obvious answer is to fit the correct size tyres, then there is no issue (unless the shell is really badly fitted).

The tiny increase in tyre width is going to make bugger all difference in your ability to drive along twisty roads, so why create a problem where there aint one?

Just my two penneth as usual :D


Nay!

The clearance on 145 tyres on an S3 is very small on both sides, indicating that the bodyshell is centralised, but 155 tyres do rub slightly on the shell on normal circumstances & may rub more when hot or partially deflated etc. 155 tyres also aggravate the probability of the front wheel catching on the S3 arch if the suspension is down on a slight corner.

Hence my Elan S3 was fitted with S4 wheel arches at the rear as well as the S4 nose & arches on my first prang (when I had owned it only a year in 1970ish).


I did say may Bill :wink: Some certainly claim to ....... I suspect there are slight variations in the shape and thickness of the inner arch mouldings from car to car. Hand lay-up of fiberglass is not exactly to precise tolererances

But I repeat, why create a problem? Fit the correct tyres on the correct rims and the job's done :D
John

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