Re: [DML] Lotus engineering

[mike.griese@xxxxxxxxxxxxxxxx]

I don't understand your issue Claude.  You should choose the
tire and wheel combination to suit the application.  The diameter
of the wheel is not an indication of the quality of the engineering.
Have you seen the F/R tire size differences for Formula 1 cars of
the era?  By your reasoning, those cars were even more
"poorly engineered".

The point is that Porsche did not use the same size tires front 
and rear like you stated.  They may have used the same wheel 
diameter, but that does not mean that the tires were the same size.

Porsche used 195mm wide tires in the front, 215mm wide tires in 
the rear as their stock tire.  They had 16" options at the time that
were 10mm wider front and rear (205/225).  The aspect ratios on 
the standard wheels/tires work out such that the front tires have 
about a .2" smaller diameter than the rears (24.98" dia front, 25.16" 
rear) for the standard wheel.  The tires are not the same size, as 
you stated.  You cannot swap front for rear.

DeLorean did have a larger difference front to rear, 195/60HR14
front vs 235/60HR15 rear, which leads to a 3.1" larger diameter
at the rear (23.21" dia front, 26.10" dia rear).  They could have 
chosen a 15" front wheel, but that would have led to a 50
series tire on the front, which has a stiffer sidewall. Stiffening
the front suspension increases oversteer, so that would have 
been the wrong choice.

According to the Car and Driver DeLorean vs The World article,
the DeLorean had an identical .77g in a 282ft skid pad as the 
911SC with the option tire of 205/55VR16 front and 225/50VR16
Pirelli Cinturato P7. The DeLorean was running the standard H-rated 
NCTs.  The DeLorean had the 35/65 (or 38/62 depending on the
article) weight distribution to contend with, Porsche had a much 
milder weight distribution and weighed 10% less (the closest weight
distribution I could find online was 50/50 for a 1972 911).  
Consider also that Porshe had been developing the 911 for about 
15 years and Lotus had 18 months, I'd say the tire choice was 
pretty darned good.

--
Mike


-------------- Original message from "cbl1739" <cbl302@xxxxxxxxxxxxx>: -------------- 


> Nitpicking.... 
> 
> 15" FRONTS 15" REARS Delorean 14" fronts MASSIVE 15" rears to 
> compansate. On the Porsche..they engineerd/were confident enough to 
> put same size DIM. tires... basically the same size tires(15")...I 
> don't get your point???? Try putting same size tires like that on a 
> Delorean and then do some top speed backroad driving.Guarenteed to 
> have a parts car :=( 
> 
> 

[Non-text portions of this message have been removed]



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