Tyres for elan

[pamitchell]

Re Vredesteins Sprint+ 155R 13 82T.
I queried Vredestein Tyre Information Center a while ago.
They replied;
Section Width 157 mm 6.18"
Overall Dia. 588 mm 23.15"
Rim. 4.5J
Rolling circumference. 1765mm 69.49"

I have no data on my Dunlops 175.70.13. Will I see any significant variance in speedo accuracy? I appreciate receiving the calibration spreadsheets but my background is in economics not engineering. We're never expected to be precise!!
The suspension & race shop I used for alignment told me I would experience better handling dropping down to 155 vs. 175 as the radial sidewalls will be less bowed on the 4.5 rim with less sidewall flex. They told me the Elan was "over tyred" w. 175s on the 4.5 rim.

[msd1107]

Phil,

Sorry, I am the son of an engineer, so I am doubly cursed with the idea that technical understanding is the lingua franca of the average person. By the same token, I have difficulty following some of the theories propounded by some of our economists! And my CPA girlfriend gave up on teaching me the elements of accounting.

The 155-13 tyre has a nominal rev/mile figure of 913. The 175/70-13 is a nominal 917. You should see no difference in odometer or speedometer readings.

Your race shop is correct in recommending a narrower tyre for the 4 1/2" rims. These rims may have been adequate for the original 5.2-13 and 145-13 tyres on the original Elan, but they are definitely at the narrow end of the recommended range of rim widths. With wider tyres, they need lower tyre pressures than recommended, which compromises cornering and braking performance.

Lotus went to 5 1/2" rims on the +2 which used 165-13 tyres. I upgraded early on in my Elan to 5 1/2" rims and 165-13 tyres. This allowed me to run slightly higher tyre pressures than with the 4 1/2" rims. The steering was quicker and more precise, and the handling noticably better. And the car retains its stock appearance.

Although you could retain 5 1/2" rims with 175/70-13, 185/70-13 or 185/60-13 tyres, those tyres would benefit from 6" rims, but you would have to go to after market wheels for that.

Early Elans (S1 - S3) had speeedometers with 1000 turns per mile (they read to 140 mph).
For 145-13 tyres and 4.11, 3.9, 3.77, and 3.55 diff, they required 27, 26, 25, and 23 teeth on the transmission driven gear.

For 155-13 tyres and 4.11, 3.9, 3.77, and 3.55 diff, they required 26, 25, 24, and 23 teeth.

For 165-13 tyres and 4.11, 3.9, 3.77, and 3.55 diff, they required 26, 24, 23, and 22 teeth. (Note, 22 tooth gears do not seem to be available)

S4 and later Elans had speedometers with 980 turns per mile (the speedometer reads to 130 mph)
For 145-13 tyres and 4.11, 3.9, 3.77, and 3.55 diff, they required 28, 26, 25, and 24 teeth.

For 155-13 tyres and 4.11, 3.9, 3.77, and 3.55 diff, they required 27, 25, 25, and 23 teeth.

For 165-13 tyres and 4.11, 3.9, 3.77, and 3.55 diff, they required 26, 25, 24, and 23 teeth.

Tongue in cheek, when Lotus went to 165-13 tyres, it was easier getting Smiths to produce a 980 tpm speedometer than to get Ford to produce a 22 tooth gear.

And by the same token, an early Elan upgrading to 165-13 tyres could correct their odometer reading by swapping in the 49 tooth odometer gear from a S4 speedometer in place of the 50 tooth original. There are web sites that go into this disassembly reassembly process in detail.

David
1968 36/7988

[pamitchell]

David;

Thanks for your detailed response! Very much appreciated. I note our cars were built in the same period in 68. Mine was first licenced as a 69. Unfortunately the factory had no record of the actual build date or delivery dealer but I suspect it went to a St. Louis dealer.
My plan is to use the original 4.5s and drive the heck out of it this year. Trips planned to Mendocino & Yosemite. Would you advise keeping the tire pressures @ 19f/24r for the 155s?

[Rob_LaMoreaux]

My stock wheels have 155R13 Michelin MX4 tires and they are not to my liking. They squeal terribly at any attempt to make them work, and they are too hard to get much grip.

The Panasports have 175/60R13 Yokohama A032Rs for track and autocrossing. They work fairly well, but being lower profile they are more sensitive to camber change on bump. I started out with the H compound and found that for autocrossing it did not get up to temp. The S compound works great for autocrossing and at a time trial it wasn't until the last of 4 timed laps that they started getting too hot.

Unfortunately the A032R is no longer available in the US, so I bought some A032R SRF compound tires on closeout. These are the Spec Racer Ford version, so will probably be between the S and H compound.

In the US there is nothing decent for the Elan, since all the manufacturers are discontinuing 13 inch tires except for their economy car versions that are too hard to work. The XAFFs are available at really high prices. The Vredesteins might work well but I don't know enough to say.

I'd love to find a nice 175/70R13 tire with a treadwear rating around 200 for everyday (I have an S4 with small springs), but I think they all have been discontinued in the US.

Rob

[msd1107]

Phil,

Yes, I noticed you had an early S4, even earlier than mine. Mine was also registered as a '69. I got it from a dealer in San Diego in '81 after my first Elan perished in a fire and my wife and I couldn't find anything suitable with which to replace it. Mine has Webers, does yours?

With respect to tire pressures, the factory recommended 19/24 pressures are suitable for around town use where ride comfort is more of a concern. The recommended high speed pressures of 24/29 give better handling and steering responsivness and fuel economy at the expense of low speed ride and the tire wearing in the center (not to much of a concern with current tread wear ratings).

Rob,

I have gone through the same heartache as you. I used high performance 155-13, then 165-13, then 185/70-13 and finally 185/60-13 (these are much too small in diameter). Since my car is in pieces now, I am thinking outside the box and considering converting back to bolt-on hubs, getting light weight 15X6 wheels and using 185/55-15 tires. (Virtually same rolling diameter as 155-13). (I use small diameter springs and have relieved the inside of the fender wells to provide clearance). The tires are available in high performance versions here in the states. The combined weight of the hubs, wheels, and tires will be compatible with the stock hubs, wheels, and tires. The concern is that tires in 185 section width are disappearing as surely as 13" tires have.

The larger wheels also allow reversion to the original steering lock the Elans had with the first 5.2-13 and 145-13 tires for the original tight turning circle.

David
1968 36/7988

[pamitchell]

Thanks David!
I"ll try the tire pressures when I get on the road. My car is a Federal car w. Strombergs.

[SADLOTUS]

Seen this? :

http://www.carbibles.com/tyre_bible.html

[mac5777]

Hello Sadlotus,
I have seen parts of that report but your site "tells All" It has been added to my favorite Bookmarks.
Sarto

[steveww]

What an excellent site, could do with some more Lotus content though

Beware fitting wide tyres to an Elan, the suspension geometry is not really designed to keep the wide footprint flat on the road through the suspension's travel.

Given the light weight of the Elan wide tyres may make the Elan float on water IMHO wide tyres loose the delicate touch the Elan has.

[bcmc33]

What do you mean by 'wide tyres'?

I plan to fit 175/65 to 14" wheels - is this in the 'wide' range?

[GrUmPyBoDgEr]

Hi Brian,

for what it's worth:I've got 175-60 x 14 tyres fitted to my 185 bhp Zetec S4 & it does get very fidgety in the rain especially when in the depressions left by heavy traffic in the tarmac.
I expect engines with lesser power/torque would not be so sensitive.
What people are writing about the higher loading on the smaller footprint of the narrower tyres being better is technically correct.
I've not gone back to 155's to try to prove any theories, being very happy with the wider ones in the dry.
IMHO With increased tyre pressure the Elan's reactions are just as "nimble" as with the standard width tyres.
Tyre pressures is something you will have to play with.

Cheers
John

[collins_dan]

For US 13" tires, I was thinking about going with Toyo RAs. Here's a link to a site that carries at a very reasonable $137 per tire.

http://www.frisbyracetire.com/toyo_ra.asp

They also carry Toyo R888s for $141.

I have had the car for 4 years and run 185/60R13's. I don't know what the car would feel like on narrower tires. It feels very nimble on the 185's, but the current set are from '99 and have gone hard.

I would consider 14" or 15" wheels, but getting a lotus knock-on is a real challenge over here, not to mention an expense.

Dan

[guerrilla garage]

David mentioned getting a lightweight 6x15 wheel and using 185/55x15 tires. I was looking at the sizes and considering maybe a 5.5x15 wheel and a 195/50x15 tire of which there are a lot of choices. The diameter is 22.7 which is just about close enough to stock. I figured a 5.5" wheel had a better chance of clearing the spring perch and bodywork. I'm really surprised that nobody has put together a "group buy" from Panasport or one of the other manufacturers of Minilite clones. I'd offer but that kind of thing is so far outside my area of expertise it's silly. If it were to happen however put me down for a set of "knock off" wheels. -Steve

[bcmc33]

John,

I did think about 185/60x14 as it gives the same rolling radius as 155/85x13, but did think that they would be too wide.


One thing that has always puzzled me is the mantra of wider tyres to get more rubber on the road. Assuming the same tyre pressure, the area of footprint will be unchanged, only the shape of the footprint will change. I am assuming that tyres do not have a way of avoiding the laws of physics.
So in looking at the shape of the footprint, it may be reasonable to see how wider tyres give worse grip in the wet as it is presenting a wider narrow band of contact with the road in the direction of travel. However, it has been my practice over the years to increase tyre pressures when I expect to be driving hard and fast ? now this must have the effect of reducing the footprint but increases sidewall stiffness. And I was always being told in by the faster racers in my ancient sprint and hillclimbe days that sidewall stiffness was the most important factor for grip.

Please discuss and post your essays here.

BTW, the tyre I am considering buying is Vredestein Hi-Trac. Does anyone have experience of these? I did look for Vredestain Sprint but it does not seem to be a UK tyre.

[collins_dan]

Notice he mentioned going back to bolt-on's... the issue is Lotus "peg drive"/ "knock-offs". After much back and forth with Superlite, it doesn't appear that they offer a Lotus peg-drive option. We reduced the options to Panasport and Minilite. As I recall, Panasport only offers a 13" x 5" Lotus peg drive. For 14" or 15", Minilite seemed to be the only option. Pricing was over $1,300 delivered to the East Coast. Here's the US dealer's info:

John Targett
TargettMotorSport Ltd, for
Minilite Wheels,
550 Crystal Lake Road,
Akron Ohio 44333 USA
Cell: (00) 1 330 283 3668
fax : (00) 1 330 666 6269
www.minilitewheels.us