Tire (Tyre) Question

[MoPho]

Thinking about going to 13" wheels and tires from my 15" 195/45 all around. Avon CR500's are becoming extremely expensive and difficult to get here, so looking at Toyo R888's in a 185/60/13 ft and 205/60/13 rear.
Car is a Superlight R with 205hp (R400ish)
My question is should I go with the 205 in the rear with this level of power or will it create understeer? If that is the case should I put the 185 on the back?

Any reason not to go to 13" wheels? Car is mostly used on the road, doesn't seem like ground clearance would be a big issue.

Thanks

[harry b]

I got an HPC with about 230HP XE engine, have had both 13" and the original 16" wheels.
Do about the same as you, mainly road and occasional trackdays.
The nature of the XE engine is very torque and limited to 8400rpm.
This said, the 13" wheels push my engine in the higher rev range, with lots of wheelspin, a thing you don't really need with touring, even fast touring.
The biggest advantage with the 16" wheels is, It does 60mph in first gear. How fast? most of the times with wheelspin and faster then anything else around.
70mph is under 4000rpm in fifth gear.

I know, the 13" are lghter, and might have many more advantages, but for the use I have 16" are perfect.


I ended up selling the 13" wheels.

[grenpayne]

MoPho, there's no reason not to go with 13" wheels and actually many people prefer them and do as you are suggesting and 'upgrade' to them from 15" ones.

I'm not expert but I seem to remember reading somewhere that 180bhp was the right crossover point to put 8" wheels on the back with 205s on. I have about 170bhp and with 6" wheels on the front and 8" on the back I get no understeer at all. The car has (from memory) around 1.5 degrees of negative camber on the front and the rear ARB set somewhere in the middle and with a gentle dab of throttle mid corner the back end pops out very nicely

So I would say do it and you will love it!

[MoPho]

Thanks for the replies