tyre size - Will 215/65 x 14 be OK on P6

G

gully

New Member
I want to improve the tyre performance on my 1976 3500 P6 and plan to have the 14" wheels widened to take a Michelin XMI 215/65 x 14 tyre.

I do not want to go to a bigger wheel diameter as I really like my original wheel covers which look very retro and even better with the thin 1/2" whitewalls that I have added to each of the Pirelli tyres.

I would appreciate any advice on whether this width of tyre and profile (@ 215/66 x 14) will result in any problems for me.

thanks



GULLY (In Sydney)
 
Sorry Gully! Maximum width that will go in standard rear wheel arches is 205 - and then you have to be extremely precise to get the wheel offset spot on, ie the tyre has to run absolutely exactly in the centre of the wheel arch. The problem area is at the front of the arch between the boot sides and the base unit's D post. If you were to do surgery to the D post you might gain just enough to get 215's in but you'd have a terrible time getting the wheel offset right (almost certainly by trial and error!).

There's no structural problem with thinning the D post. The first stage is to lose the inner skin (it's double skinned), but to go further and chop back the whole of the D post has implications for where you're going to mount the sealing rubber for the back door aperture. Not impossible, but a challenge!

If you were to really go for it there is a second problem area waiting in the wings (ha ha). That is clearance against the rear De Dion radius arm which runs from the top of the de dion elbow back to a pick up point on the sides of the boot. This is straight on 4 cyl cars and had to be cranked to clear the (larger) tyre on the V8. Presumeably if you solve the D post problem this will be next in line!

If you get that far then any competent body shop ought to be able to put a bit of flare in the outer, bolt on, wing to give you more space. It does, however, get quite restrictive for getting the wheel on and off the hub. The racer running in the classic saloons series here has the entire rear wing hinged along its top edge to overcome this!

The other consideration with tyre size is the rolling diameter. I use a handy calculator on the Dutch SD1 site to give me the correct profile. Tyre Calculator This gives 215/70 X 14 or 195/75 X 14 as good matches on diameter. For a 205 section correct diameter is halfway between 70 profile and 75 profile in 14". It's worth checking availability of tyre sizes for 14" - I believe at least some suitable sizes are only available as van tyres, but not having needed them myself I haven't done the research!

I know of quite a lot of cars running under diameter tyres. This of course lowers the effective overall gearing, but does pull the tyre back slightly from the D post area. I've never seen a car running over diameter tyres to increase the gearing - that might be an interesting experiment with a scrap tyre to see where you run out of clearance!

I've previously put up threads about using the SD1 Vitesse 15" wheel. This needs about 3.5 mm skimmed off the bulge at the rear which mates onto the hub to give perfect offset for use with 205 section tyres and a standard D post. It also needs some relief in the area around the front hub grease cap. Using a 15" wheel has the advantage of being able to get a perfect match on rolling diameter with 205/65 X 15 tyres, which are easy to buy in high quality makes.

Hope that helps.

Chris
 
Hi Gully,
Ive recently been lucky to get hold of some good and proper p6 14" chrome rostyles,and fitted 195/70 vr 14" Dunlop sp sports to them. the difference in handling & road holding is amazing!! even just this small change over the std tyre!! as always, make sure your wheel alignment is spot on,as they can wear out very fast if its not right. I also have fitted a set of " I think were dealer supplied for towing in the 70's " basic adjustable rear shocks and have them set at medium, not to hard or soft!! preventing excess body roll and its a pleasure to drive!!
good luck with yours
dave
 
Hi Chris...Hi Dave,

Thanks so much for your insights into the challenge of fitting improved tyre width and selection onto my car....I just knew that there would be "ISSUES" with this project !!!!

I do not want to start widening the guards as I am keeping the car as stock looking as I can (see later comments !!!) so I will now explore the 205 width option with local tyre retailers here in Sydney.......from memory there was little choice in this size.

Dave, the 195 option also sounds good.......it all boils down to the choice of tyres that I can get......money is not an issue here......I just want to have a great tyre on the car......you mentioned shocks !!!.

I have already fitted Bilstein shocks on all four corners of the car. The car is also lowered 50mm in the front and 20mm in the rear so hopefully this will not add further complications to my final tyre set-up.

I am assuming that I cannot safely fit a 195 tyre on my current standard tyre so at this stage I am probably more inclined to go to 205 if I am going to spend the money to get 4 wheels widened....again it will all get down to the tyres that I can source.

Again....many thanks guys for your input.

PS: I plan to post some pics of my car when I get from the trimmers in a couple of weeks !!!!!

All the best


GULLY (In Sydney)
 
In the UK it is now illegal to split and widen steel wheels, I think the law on it changed a few years back. Probably of little importance to you being in Oz :D
 
Gully!!!
dont split your wheels!!!
fitting 195 or 205 to proper v8 wheels shouldnt pose a problem for normal driving!! Fitting them to the thinner 2000 wheels may though!! they do look the same ???
 
Mine runs 195/65 R15, on P5 Rostyles.

The biggest issue I have found with a P6 handling right, is the rear springs and shocks. If these are worn out, and the back end of the car is riding in the weeds, you have got no chance of good road holding, especially in the wet!
Shocks that are too soft are a definate no as well. I recently put new rear shocks on the rear of mine, and on an undulating road, it's like a tramp steamer on the rolling sea. I'm putting the old rear shocks back on, as they're stiffer :;):
 
Gully, as you have found out, 14" performance tyres are thin on the ground here in Australia. BF Goodrich still make a few 14" tyres, the best bet would probably be their Sport T/A's. They are a very good tyre, I ran some on a Valiant I had (cursed with factory 14" alloy wheels). ALl the other 14" tyres I could find were "touring" tyres, not really worth the effort.
I am looking at having my hubs redrilled to suit the Ford stud pattern, then I can buy some realisticaly priced 15" rims.
Otherwise, as you have said, you get the stock rims widened, which they do by removing teh centre disc from your wheels and welding on a widened rim.

Regards, Andrew.
 
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