Caterham 16 inch wheel/tire questions

[athens7]

I'm due for new tires before autocross season starts. I want to fit tires that are streetable, but as aggressive as possible. My choice was a set of Toyo R1Rs, which are one of the very few types available in 205/45R16 like the original Avon ZZ3s. When I went to have them installed, I found they were too wide, and rubbed against the wing stays (I had been warned that this was a likely possibility). Another choice is the Bridgestone RE-11, but I fear the same problem will exist with them. I am told most of these types of tires are bigger/softer than sized as a way to shade competition rules. A 5 mm spacer would allow the tires to clear the wing stays, but it looks like they will then contact the outer lip of the cycle wing. I would prefer to avoid the extra expense of new wheels, and I cannot use a tire with a UTQG less than 140 (R comps) without making a number of other modifications to the car to remain legal, so Advan A08s or Toyo R888s are out. Can anyone recommend a tire/size to fit my wheels? If I must go to a 15" wheel, what are some good choices for light weight? Is the Caterham 15" wheel any good, or am I better off with an Enkei or other aftermarket wheel?

[Elv15]

Can you simply bend the wingstay?

[athens7]

I've never been able to SIMPLY bend anything! It is one possibility, though. What is the best point in the stay to bend-up at the wing, I would guess?

[Doug Liedblad]

I was able to bend my wingstays so that a low profile 16" tire would fit. I don't recall the size but can find out. I think they are 205/45 R16.

I removed the cycle wings and bent the stays in small increments until the tires cleared. They clear the cycle wings just. The part over the top of the tire might slant up a bit. You can tell what parts need to move when you go to fit them with the cycle wing off.


The reason for the 16" wheels and tires was to reduce RPM at freeway cruise. This part of the plan worked fine.

HOWEVER:

the 16" wheels and tires are so much heavier than the stock 14" that they make a significant impact on acceleration. When compared to the 13" lightweight Kodiaks with ACB10s it's very dramatic.. The 13" Kodiak + ACB10 weighs about 20 lbs. The 16" tires alone weigh more than that. You pay a real penalty for increasing rotational mass and the larger diameter tire just makes it worse.

NOTE: ACB10s need to be hot to work so aren't a good autocross tire.


I'd recommned spending the money for the lightweight wheels and really sticky tires for autocross. Probably one of the cheapest ways to be sure you are making the best use of the horsepower you've got.

Anybody want some nice 16" HPC Wheels?

[athens7]

I looked at the Kodiak web page after reading a recent thread here; their wheels are impressive, both lightweight and attractive. Thanks, Doug, for your explaination of the 16" wheel application. I always figured the wheel choice was made by Caterham to put a bit more rubber on the road, and to fit in with the 'bigger is better' wheel aesthetic that seems to predominate with the public these days. I am turning 3500 rpm at 70 mph with a 3.92 rear and standard ratios T-9; I would prefer that not to go up. Do you know the weight of the Caterham 16" wheel? As you noted, the tires for this wheel run anywhere from 19-25 lbs. If I were to change, it would be to 15s, not 13s, and I'm not sure how much weight I would save. What I can save by staying with 16s is $$$, which in this economy is in somewhat shorter than usual supply! My mechanic feels he can adjust the stays to accomodate the R1Rs, which, at 19 lbs, are some of the lightes tires available for this wheel. Since they are likely only good for one season, and are a big improvement over the ZZ3s, I can always revisit this issue next year. At this point, grip is most important, as I can spin the rears from start to redline in first and break the rear end loose on anything other than a perfectly straight line in second when hard on the throttle. It's a bit frustrating to know your run is toast in the first few seconds because of a bad start!

[Rod]

Radius

I think the weight of the wheels is important, but I think acceleration is more impacted by the radius of the wheel.
I have two sets of Kodiak rims, a 15 inch set and a 13 inch set. On the 15 inch set I have CR500s for street and I have ACB10s on the 13 inch rims for track/race. There is not a significant weight difference between the two, but the acceleration difference is phenomenal.

[Doug Liedblad]

I agree, the radius is part of the equation.

Going from 14" wheels to 16" wheels really took some of the snap out of all aspects of driving the car. Not just acceleration.

It's more an overall feeling for the car.

I've used the 14" on track and off, they are OK but you can notice the improvment going to 13".

Nice and lively on the 13" with a much heavier feeling on the 16".

With 14" wheels and tires and a 3.92 diff ratio, I'm 4000 RPM at 70 mph which is why I bought the 16" wheels. The overall behaviour of the car was changed so much I'll live with the 4000 rpm buzz until I get the 3.62 diff installed.