Tire Pressures?

[Richard Gibson]

I purchased my first 7 this past year. It came with Spax adjustable shocks on all 4 cornes. It has new 205/60-13 very soft tires which are similar to the Yoko A032R. I am totally lost on what air pressure to run. Can some one give me some starting points for the front and back. Also, the car is an 85' live axle and has 14K miles. I assume the shocks are 15 years old. Should they be replaced, and if so, what are the opinions on Spax and are there any better shocks available.

 

Thank you

 

Richard Gibson

Washington DC, USA

[Alex Wong1697456877]

205 all round? Probably a bit over-tyred, especially at the front. What tyres are they? 18 psi all round is a good starting point. I tend to put more in the fronts and less in the rears. 26/18 for 021R's and 18/15 for ACB10's, but these are just what works for me.

 

 

 

Alex Wong

www.alexwong.net

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[Dartmoor7]

Caterham recommended

pressures from the handbook

185/70x13 20psi

185/60x14 20psi

195/50x15 18psi

205/45x16 16psi

(Your tyres are non-standard)

Jerry Parker

L7 SVN

Caterham 1.4 Supersport

 

[Fast Westie]

Richard

Spax shocks last anything between 10k and 40k miles on a 7. Alternatives you can consider are:

AVO http://www.avouk.com

Nitron http://www.nitron.co.uk

Leda http://www.ledasuspension.co.uk (??)

Bilstien Available from Caterham

 

As for tyres (or tires smile.gif) 18-20psi should be about right. Try this and see how the car handles.

 

[Richard Gibson]

Thank you for all the info. I think I have ben running at about 20 psi, So I am in the right ballpark. Alex, in saying a 205/60 is a bite to much tire, do you think it would be OK to run 185/60 up fron and keep the 205/60 in back? I was concerned about clearance (I'm sure everyone is) and was thinking 185/60 all the way round would be very low. Here in Northern Virginia, outside of Washington DC we have great twisty and well kept roads, but manhole covers and transitions can sometimes be scary. Plus the new thing here is putting speed bumps up on many roads to keep traffic away from the sidestreets. These speedbumps are set up so you can do 25MPH over them and are very long and flat, but still tall. I always hit my exhaust on my Lotus Elan.

I am very concerned about the oilpan. I think I remember Alex losing one at some point.

 

In regard to the tires I have BF Goodrich R1. It is a tire almost exclusively used in autocrossing. It is about the most sticky tire you can buy that is DOT legal. Basically after a few miles they look like an F1 tire. I have seen Avon tires in low flying that look similar, but they are not available here.

 

The Spax shocks are probably in good condition w/ 14K miles since the car was garage kept and not a ding on it. I guess I am wondering if the Spax is the up among the best available for the car.

 

Again, thanks for the input. It is nice to have such a well educated forum at my disposal.

 

Richard Gibson

[murph7355]

I have 185/60-13 and 205/60-13 on mine and it works really well.

 

I'm with Mike that 205s on the front are a bit much...

 

If my maths is OK and assuming the tyres do exactly what they say on the sidewall, the 205 fronts buy you about 1cm of additional clearance over the 185s. I think you'd be better off accounting for this by adjusting the shocks rather than fitting the wider tyres. Your steering response should then improve allowing you to better avoid the manhole covers and bumps (believe me this country is blighted with rubbishy road decoration too!)...

 

FWIW I run mine at 18psi all round and it seems pretty good. Once I get some track time sorted out next year I'll have a bit of a play with different settings, but unfortunately it's time I admitted to myself I'm no Ayrton Senna so can't tell if one wheel is 0.5 psi down. I'd probably be pushed to tell if they were 5 psi down! So I'd say anywhere between 15psi and 20psi will be in the right area.

 

 

 

 

 

 

C7 AJM

[FH]

Hi Richard! Try "traversing" over the speed bumps - i.e. one wheel at a time at an angle - in the way you would cross a gulley in a 4x4. It may look slightly ungainly but you'll clear the offending traffic calmer with your underneath bits still intact.

 

[captain chaos]

On a slightly different line of thought. I was told to pump up my tyres to about 40psi during this winters storage to help eliminate flat spotting the carcases. Comments please?

[Michael Peterson]

Richard:

 

If you are concerned about your pan contact J. Bigler on the for sale section of this web site. He is marketing an improved clearance cast sump. He is in the U.S. and may be able to help.

 

Cheers

 

Michael

 

Ann Arbor, Mi.

[FE600]

I am planning to use that combination of tires, ie 185/60/13 and 205/60/13 on my PRB. Any sugestions as to the ideal rim widths for these (A032R's) tires? I was thinking of copying the R500 line of 6 1/2J and 8 1/2J rim size. Is this too wide, or this just the ideal for handling? Seems very wide to me.

Regards Stuart