Lotus Elan

Tyre question?

PostPost by: dougal cawley » Tue Jul 31, 2018 10:15 am

I would love to know your impression of 145.

I would think they will be lovely to drive on, I would expect 155 to give better lap times, but i would expect the 145 to be nicer to drive on. light with a really fast and precise turn in.

i don't think you lock up your wheels under braking, and i don't think you get too much wheelspin.
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PostPost by: Gray » Wed Aug 29, 2018 1:05 pm

Hi

Just to fuel the debate re low profile tyres on an Elan, the August 69 price list attached included Goodyear low profile tyres for the Elan. It does not list the size, 70 series were being introduced around then, I believe 165 was the maximum width recommended for 4.5 inch rims so presumably 165/70/13.

I'll ask again if anyone has manufacturer's current recommended minimum and maximum tyre and rim widths?
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PostPost by: Barney » Wed Aug 29, 2018 7:00 pm

dougal cawley wrote:Do any of you guys still run 145R13 tyres?


On my S2 I have to use 145s because of clearance problems with my bolt on wheels. Sorry, but I cannot comment on any comparison as I haven't driven any other combination on an Elan.
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PostPost by: mwhitaker » Thu Aug 30, 2018 6:06 pm

Hello to all from Virginia-USA,
I have enjoyed the tire choice discussions for the Elan and having recently acquired a 69 S4DHC thought I would apply this info to replace 155/80-13 Kuhmo radials on my car due to dry rot/age, etc. What I had forgotten/not realized is that all Elans are slightly different in terms of what will /not fit, so I offer this as a cautionary tale for the inexperienced.
My car was fitted in past with 12 inch-120lb springs and I think TTR/GAZ front dampers with a chassis change 30 yrs ago probably with mild body settling up front. At first, I noted a bit of bump steer and that the drivers side lower spring perch was 8 threads higher and with medium to hard damper setting compared to the other side. After lowering the perch/changing the damper setting to equal the other side, the steering felt better. I then chose Michelin XAS 155-13 to mount on my 5 x 13 inch Panasposts after comments on this thread, particularly eloquent from Dougal, convinced me they were the best choice.
Of course, I had inadvertently lowered my ride height on the drivers side, decreasing fender clearance with subsequent cracked fender arch on the drivers side and rubbing of the front fenderwell fiberglass on both sides. Now I know why the drivers side was elevated! Admittedly, this was after suspension settling with a chap of 18 stone in the drivers seat! (not me by the way )-Anyway, I found even my spare with 155/80-13 seemed a bit tight-so I over compensated and found Achilles 155/70-13 tires to fit which work well with nice steering feel, turn in and decent ride. Also, dirt cheap at $40 ea with free shipping from tires-easy.com. Bridgestone 165/70-13 NA in the USA now and I wanted to stay with original width even if rolling diameter is less, thus lowering gearing a bit.
I am not giving up on my Michelins and will search out original/reproduction 4.5 x 13 inch steel rims for eventual fitting as I want the Michelin feel/construction. However and this is the major point, not all 155/80-13 tires have the same rolling diameter on a rim -with the Michelins at 23.2 inches vs typical 155/80-13 rolling diameter of 22.8 inches. Currently I am at 21.6 inches with the 155/70-13. I wonder if Michelin fitting is possible with raising the lower perches more and how much I can get away with to increase clearance without going too far. I did raise them about 3/8 inch after replacing the tires, so I guess we will see. Any words of wisdom are greatly appreciated and hopefully this helps those looking to replace their tires. This site is pretty bravo and a great help to owners like me.


Cheers, Mark Whitaker

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PostPost by: Gray » Fri Aug 31, 2018 7:56 am

Mark

I don't know the offset of the panasport wheels compared with original 4.5 inch wheels. Clearances vary from side to side and car to car even if they have not been damaged and repaired. I also saw new front sections from Lotus back in the day which did not fit that well. New 4.5 inch wheels might solve your problem with your new 155 XAS, but the suspension height should be set up to give the right ride height as I'm sure you're aware. Sue Miller is getting new 4.5 inch wheels remade, so probably your best option.
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PostPost by: alan.barker » Fri Aug 31, 2018 12:25 pm

With the adjustable perches the first thing i would look at is ride height. Also Is the front of the car lower than at the back.
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PostPost by: mwhitaker » Sat Sep 01, 2018 1:56 am

Thanks to Gray and Alan- makes sense to correct ride height and I plan on exploring the 4.5 inch wheel repros via Sue Miller- not sure about Panasport offset either. Then as long as I am torching the credit card, I can justify a new set of three eared spinners instead of the octagonal wheel nuts I have now!


Thanks again, Mark
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PostPost by: mwhitaker » Sun Sep 02, 2018 8:53 pm

Hello-

Spent the morning measuring chassis clearance, fender to tire distances and right height using Brian Buckland's excellent reference manual. After adjusting my front spring perches and allowing for decreased rolling diameter of my 155/70-13 tires, my measurements are right on the money, and the front wheel arch clearance has not only improved but appears symmetrical from side to side. With toe in set at 3/32 will leave everything as is for a bit and enjoy the car before springing for Sue miller's steel wheels. I think I have adequate clearance now to fit the Michelins-thanks to your help. Guess I was doing the horse before the cart sort of thing with initial tire fitting!


Cheers, Mark

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PostPost by: alan.barker » Mon Sep 03, 2018 5:50 am

Well done Mark,
now you can start with a good baseline but first get out and drive your Lotus :mrgreen:
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PostPost by: dougal cawley » Mon Sep 03, 2018 3:19 pm

Gray wrote:Hi

Just to fuel the debate re low profile tyres on an Elan, the August 69 price list attached included Goodyear low profile tyres for the Elan. It does not list the size, 70 series were being introduced around then, I believe 165 was the maximum width recommended for 4.5 inch rims so presumably 165/70/13.

I'll ask again if anyone has manufacturer's current recommended minimum and maximum tyre and rim widths?


for the sake of the handling discussion; the Goodyear low profile tyres offered by Lotus here, will be a facr cry from any 165/70R13 tyre that you can buy currently. the carcass structure will be a very different thing, designed to work on a very different kind of car. the carcass of these Goodyear tyres will be more similar to the Pirelli CN36 https://www.longstonetyres.co.uk/pirell ... /cn36.html that we offer for later cars.

I think 1969 was the year when Lotus changed to 155R13 from 520-13 crossply. the 145R13 https://www.longstonetyres.co.uk/pirell ... -ca67.html willl be lovely on these early cars. i would suggest that fitting a 165/70R13 modern tyre on these cars will be cheap, but won't handle very nicely.

Also when you get involved in fitting modern profile tyres on cars that originally fitted crossply tyres, then you will find they are very much a different shape. the widest parts of the tyres are at different heights on the tyres. the point to be most wary of is that the tread on a modern low profile tyre is nearly as fat as the widest part of the tyre. so a 165/70R13, theoretically will be 165mm at the widest point of the tyre, but the tread width will be nearly that wide too, however a 5.20X13 when they made them back in the day was 140mm wide, but the tread may well have only been 100mm wide (ish).
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PostPost by: dougal cawley » Mon Sep 03, 2018 3:22 pm

Mark.

Is your car one of the earlier cars that should have the smaller tyres?
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PostPost by: alan.barker » Mon Sep 03, 2018 3:31 pm

If i understand that correctly Doug.
So when Lotus changed to Radial they increased the footprint without needing to retool for wider (heavier) rims.
That sounds like a nice Chapman move. No increase in un-sprung weight and better grip :mrgreen:
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PostPost by: dougal cawley » Mon Sep 03, 2018 4:20 pm

So when i look at my Dunlop fitment guide 1965-78 it lists the Lotus Elan tyres 4.5" rims throughout. (except +2 with 5.5")

It says:
1500 1965 520X13
1500 66-68 145SR13
S.E. 69-71 155HR13

Lets see if i caan do some technology:-

65-78-fitment.jpg and


I think that worked
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PostPost by: Gray » Mon Sep 03, 2018 4:42 pm

Dougal
Thanks for the update. I take your point that a modern radial will have a much wider tread than the equivalent old crossply.
As far as I’m aware Lotus changed from crossply to 145/13 radial on the S3 Elan – I think they were an option? - and then to 155/13 as standard on the S4 when they changed the shape of the wheelarches, but no changes were made to suspension, just longer limiters on the steering rack.
I have gone down the route of Spyder chassis/suspension and 14x6 minilte style wheels, one of the reasons was the lack of good high performance tyres for 13 inch wheels at the time. I’ll find out if this was a good decision when the prolonged rebuild is finished (still doing the 26R arches)!
I note that some have put modern 175/70 tyres on the original 4.5 inch wheels. I thought 165 was the maximum width for 4.5 inch wheels (assuming clearance is available), do manufacturers issue any guidance on maximum tyre to wheel widths for current tyres (accepting that whilst wider tyres are possible they may not be the best choice if other changes have not been made)?
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PostPost by: mwhitaker » Mon Sep 03, 2018 4:44 pm

Hello Dougal,

Thanks for your question. My car is a 69 S4dhc-build date-Oct1968 according to Andy Graham and would have come with 155-13 as standard fitment. I actually thought about the CA-67 145/13 at first but its listed inflated diameter is similar to the XAS at 23.2 inches and my original issue seemed more due to rolling diameter than width . I wonder if the profile of the Michelin mounted on original 4.5 steel wheels instead of the 5 x 13 Panasports I have now will make a difference. I really want to try the Michelins after reading your notes!

Cheers, Mark
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