Tyre pressures

[Dave6091]

Took the mk4 to a car show on sunday and got chatting to an imp owner, he asked about lower pressures as the Dav is lighter than the imp and told me the std imp pressures are 18f 30r. I didn't realise the imp had such a low front and have the mk4 at 18f 24r, it corners on rails but is quite 'darty'? on uneven roads at speed. I shall try lowering the front to 16 but what do you lot think?.
We have over 100 members now so i'm expecting loads of replies!!!!

Dave.

[intrepid]

Reply #1

I have no idea as mine's still not on the road!

I think you need to be careful going too low on the pressures as you run the risk of pulling the tyre off the rim under heavy cornering.

The wandering you experience is more likely caused by the wide wheels - we get the same issue with the Mini with its wide alloys. Perhaps worth trying cross-plys

[shammycoupe69]

The tyre pressures for the Imp are quoted for crossplies. I run 25f 35r on mine in radials, but they are a little bit higher due to the 165 tyres on 41/2J rims being a bit too wide so flexing more!

I think you are about right, not sure what Dad has in his.

[davrian6140]

I run 20psi front and 26 rear car handles well up about 100 mph but it
does move about a little after that. try softening the shocks abit.
All the best Dave

[Dave6091]

Funny you mention crossplys Cliff, I'd not had my Mk6 long (over 35 years ago, blimey!) and needed a set of tyres. I'd seen in the brochures that new Davrians were supplied with Firestone wide oval crossplys and saved up and found a set of new ones. It took about 10 secs after driving away after having them fitted to realise why all manufacturers had changed to radials and promptly did likewise!.
I mentioned this to Adrian a few years later and he had a good laugh telling me he only fitted them as Paddy Hopkirk had done him a great deal on 100 astrali wheel and tyres that nobody wanted as they were crossplys! .

D.

[motorsportjohn]

I currently run my Yokohama 205-60-13 A048Rs at 15-16psi front and 20-22psi rear for both road and track use. However in the past, with less specialist tyres, I used to set the pressures to 18 and 25psi respectively.

[cheeser]

Lots of factors seem to determine suitable tyre pressures, but one of the criteria seems to be dependent on the amount of camber on the front and the amount of understeer that is considered appropriate. Original Imps had positive camber caused by raising the front of the car to get the lights at the legal height just before being launched for sale. Not the original setup that was intended, but a quick fix and giving plenty of understeer that was considered suitable for Mr & Mrs Public!
I'm sure that most of our Davrians will be setup with a little negative at the front and probably include an antiroll bar.
Brother's Mk7 (ex Pat Longhurst) with fairly strong front antiroll bar and running road Yokohamas used 24-25 psi both front and rear but with slicks 14psi front and 16psi rear (these were 8inch front and 10inch rear rims).
My own limited experience with road tyres for a few trackdays ,front bar and 61/2 and 8inch rims I found ran well with about 28psi at both ends.Note that my car has a Mini lump, not that I think that changes things too much apart from a little extra weight, although for the road I'd normally run with less pressure but still keeping same psi front and rear.
All the info that I've heard or read seems to suggest using similar pressures front and rear with suitable camber and setup.
Hope to hear of others experiences, as has been said there must be lots of knowledge out there, or doesn't anyone check their tyre pressures?!

[m.colin]

It sounds to me that the Davrian is not too fussy about pressures. With 185/60 yoko 021's I am running 16--20. It feels great!
Regards, Mike.