Tyre Clearance Plus 2 - Wheelarches (185/70R13s)

[gerrym]

Roy Gillet wrote that he had only a little clearance when on slight lock and with slight compression.

This post is intended as a show of hands for anybody (PLUS 2s ONLY!) who can fit 185/70sR13s under their standard bodywork.
When replying to the post, please detail brand and model of the tyre, clearance side to side (the body may not be even on the chassis), whether an actual rub has been detected, steel or alloy rim.

Myself, I've got a 185/70R13 on order for a trial fitment to all 4 corners this coming weekend. Will remove spring/dampers to allow for suspension movement.

Why 185/70R13, well there's a pretty good selection of sticky rubber available in this size (Escort Mark Is?) and it allows use of the original wheels as well as almost matching the original rolling diameter and filling the wheel arches.

Regards

Gerry

[terryp]

Gerry
I have Goodyear GT70 and they clear fine apart from passenger side front where under braking it has worn a slight hole in the bodywork .
They were put on by the previous owner. If I were to replace any tyres I would go for the same. (They look good!)
Terry

[mikealdren]

Hi Gerry,
I think that my +2 shell must have had oversize tyres fitted (but I have no details) and they wore through the front of the engine bay.

Best wishes
Mike

[terryp]

Hello
Me again , the pictures above are exactly what I have in the same position.

Terry

[lotusanglia1965]

Hi Gerry,from (bad) memory,i tried vredestein 175/70x13's on my +2 and even they were too close for comfort.165/70's looked too small,so i opted for 165x13.

[Foxie]

[quote="gerrym"]This post is intended as a show of hands for anybody (PLUS 2s ONLY!) who can fit 185/70sR13s under their standard bodywork.

Gerry[/quote

Gerry,

I have Spyder IRS, 14 x 6 Minilite copies (Two Gates) Yokohama A520 and Toyo 888s 185/60, plenty of clearance.

Sean Murray

[Matt]

It seems to me Mike's issues are more with his ride height than his tyre choice

I have ran 185/70sR13s for years without any tyre fouling issues

Hope this helps

Matt

[mikealdren]

Matt,

You may well be right, I acquired the body to re-build as a Zetec car so I never saw the donor car on the road and I don't know what tyres were fitted. The post was to show the touch points on the body.

Mike

[terryp]

One small point about my holes (which are the same as Mike's) is that there is plenty of clearance on most occasions , only when the car is under a lot of braking is there any problem, and I would imagine that this could be corrected with shock absorbers /springs/ride height

[Roy Gillett]

My worry (which triggered this thread ) is that even with my 175/70/13 there is very little clearance not in relation to the inner wing which is what others are reporting. Where my tyres have minimal clearance is at the front lip of the wheelarch when the 'equator' of the wheel lines up with closest point of the body due to suspension movement. As the tyres I have are fairly 'square-shouldered', matters are at their worst when there is a little lock on so that it is the tip of the shoulder that is lining up with the wheel arch bodywork.

As I have said before there is just room for my 175/70/13s but it is cigarette paper thickness so I am sure no tyre with a larger rolling diameter would fit. Also the older style tyres have a rounder tread profile which would undoubtedly have an easier passage past the wing at the critical point mine come so close, even if they had the same rolling diameter. I have never had any problems with tyres touching the inner wings and just for completeness I run the car with the prescribed 6.5 inch (laden) ride height to the bottom of front chassis crossmember.

Hope that helps,

Roy
[/i]

[gerrym]

Mike, Terry, Roy and others.

I think there is quite a bit of milage to go on this one. (Ignoring rear tyre clearance issues with the std spring & spring pan as there are known fixes for this, and concentrating only on the front of the PLUS 2 ONLY)

The tyre size I started with (185/70 r13) in theory has a slightly smaller rolling radius than the stock 165R13 tyres fitted to the factory from new.

I have reports (please keep the PMs coming to me) of mainly road legal motorsport tyres (such as Yokohama A021s) in the above size fitting without any issues. On the other hand Mike and Terry have holes in their inner wings, Roy has effectively a rub on the outer wing lip and slight steering angles and some compression.

Can I suggest a couple of explanations which need further input from contributors.

1/ Early cars had the lower ride heights due to the shorter spring (ref the specifications section of the Lotus Workshop manual).

2/ For those suffering from rubs in their inner wing, I can't believe this happens at normal suspension compression as any driver would then stop and investigate due to noise alone. A possible cause is degradation, missing or non-std front shock bump stops meaning at full compression there is an intermittant problem???

3/ There may be enough variation in either the front fibreglass molding, std of repair sections fitted or more likely the setting of the bodywork on the chassis which results in problems for some owners and absolutely none for others

4/ The tyres that have been fitted in the 185/70/R13 size, are sufficiently rounded and/or small on actual rolling diameter that the problem has not manifested itself.

5/ There is an issue with reproduction 13inch alloy wheels having the wrong offset. (Could I have some details on this?).

Bearing in mind that one of the objects of the above investigation is to match the original rolling diameter, then please any input, no matter how anecdotal much appreciated.

Regards

Gerry

Note, going off subject slightly, Avon have a "road" tyre (albeit only T rated) in the above size which was used as the prescribed tyre for a recent Caterham race series.

[ppnelan]

If some experience fouling but others don't, it might be worth checking the number of turns lock-to-lock on the steering rack as rebuilt/replacement racks may not be to the 'correct specification'...

www.lotuselan.net/forums/viewtopic.php?t=1445

Matthew

[wparslow]

[quote="gerrym"]Mike, Terry, Roy and others.

I think there is quite a bit of milage to go on this one. (Ignoring rear tyre clearance issues with the std spring & spring pan as there are known fixes for this, and concentrating only on the front of the PLUS 2 ONLY)

The tyre size I started with (185/70 r13) in theory has a slightly smaller rolling radius than the stock 165R13 tyres fitted to the factory from new.

I have reports (please keep the PMs coming to me) of mainly road legal motorsport tyres (such as Yokohama A021s) in the above size fitting without any issues. On the other hand Mike and Terry have holes in their inner wings, Roy has effectively a rub on the outer wing lip and slight steering angles and some compression.

Can I suggest a couple of explanations which need further input from contributors.

1/ Early cars had the lower ride heights due to the shorter spring (ref the specifications section of the Lotus Workshop manual).

2/ For those suffering from rubs in their inner wing, I can't believe this happens at normal suspension compression as any driver would then stop and investigate due to noise alone. A possible cause is degradation, missing or non-std front shock bump stops meaning at full compression there is an intermittant problem???

3/ There may be enough variation in either the front fibreglass molding, std of repair sections fitted or more likely the setting of the bodywork on the chassis which results in problems for some owners and absolutely none for others

4/ The tyres that have been fitted in the 185/70/R13 size, are sufficiently rounded and/or small on actual rolling diameter that the problem has not manifested itself.

5/ There is an issue with reproduction 13inch alloy wheels having the wrong offset. (Could I have some details on this?).

Bearing in mind that one of the objects of the above investigation is to match the original rolling diameter, then please any input, no matter how anecdotal much appreciated.

Regards

Gerry

Note, going off subject slightly, Avon have a "road" tyre (albeit only T rated) in the above size which was used as the prescribed tyre for a recent Caterham race series.[/quote]

Hi Gerry - hopefully you got my reply but it's hard for me to see whether you did or not.

Wayne

[msd1107]

Wayne, Gerry, et all,

The 165/80X13 tire has a nominal rev/mile figure of 887, about 23.4" dia. However, different tire manufacturers may make the tire with a slightly different rev/mile figure. Also, the rev/mile figure increases as the tire wears. Refer to your tire manufacturers technical data sheets to find out what they say.

The greater the rev/mile figure, the smaller in diameter is the tire.

A 185/70X13 has a nominal rev/mile of 893, about 23.2" dia, about a .7% smaller tire.

The 185/60X13 is about 956, about 21.7" dia, about 7.8% smaller. 175/70X13 is about 917, 22.6" dia, about 3.4% smaller.

Interference issues are complex. Different bodies are laid up differently, they may be mounted assymetrically, the current wheel/tire may have a different offset, etc.

Also, different tires may have a different tread profile, or different sidewall width. With the proper tire, this may be sufficient to alleviate interference issues on the inside.

Generally speaking, there will always be interference at the front with the wheel cranked over and hitting a bump.

David
1968 36/7988

[Jason1]

At the Lotus factory open day 2008