ridetech tire sanity check..

[RoadRacer]

I'm always looking at 33's tires to find a set that fits what I'm looking for - getting the tire width/height/rake/pattern/usage correct is such a key part to the 33 especially if you're fenderless like mine will be (it's going on the stewart transport next week!!)

Some come close, but I'm still looking for the exact right set. The ex-Ridetech 33 comes closest, and uses the fronts I want - 295x35x18.

http://i752.photobucket.com/albums/xx162/crazyshopmonkey/ridetech%20tour/GEDC2139_zps14c9738c.jpg

But the rears (335-30/18) on that car look a little too short (height-wise). So I'm looking at 345x30x19 (so far thinking about g-force-rival)

Just doing the math, I realized something though.. the ridetech 33 rears are actually shorter than the fronts - there's a negative rake on that car, at least tire wise!

I suppose my math isn't exact to real life, but:

((295x0.35*2)/25.4)+18 = 26.1" tall
((335x0.30*2)/25.4)+18 = 25.9" tall

Is that right? I know it's slight, but having even a small negative rake seems bizarre.

[BTW, if anyone knows of a car using my current choice of 295x30x18, 345x30x19 please show me pics!)

[progmgr1]

Here is a tire size comparator / calculator that I have found useful: http://www.rimsntires.com/specspro.jsp. It allows you to see 2 different size tires side by side (although in cross section). FWIW, after long discussions with Dr. Ruth I plan to go with 245/45-18 fronts & 305/35-20 rears, which gives about a 1.7" diameter difference. Sorry no pictures - I haven't bought the tires yet.
Keith

[RoadRacer]

Thanks Keith. Yes that confirms it - they used a shorter tire on the rear, albeit only slightly. My choice will be a 1.1 inch difference front-rear.

The thinking continues ;)

[erlihemi]

Not sure, but, let's assume ridetech intentionally did a reverse rake. 2 reasons I would do that.
1. Gear ratio problem.
2. Weight transfer problem
3. Sponsor issue with tires

Otherwise they just missed it on a high dollar, high profile build, and given that its Ridetech I doubt that it's a miss.

Like those Falkens though.

[JOP33]

Here is a tire size comparator / calculator that I have found useful: http://www.rimsntires.com/specspro.jsp. It allows you to see 2 different size tires side by side (although in cross section). FWIW, after long discussions with Dr. Ruth I plan to go with 245/45-18 fronts & 305/35-20 rears, which gives about a 1.7" diameter difference. Sorry no pictures - I haven't bought the tires yet.
Keith

What backspacing and offset?

[DaveS53]

Tire size choices are often limited by what's available. You can't just buy any size you want with the same model of tire. Real hot rods often have tires that are 4-5 inches taller in the back, just for looks. If you're going to auto cross the car, then you probably don't care about hot rod tradition.

A common choice for a modern open wheel hot rod would be 295/45/20 rear and 225/45/17 front. The problem these days is you can't get these sizes with the same rubber compound and tread pattern anymore. That's what I have on my fendered car, but those BFG tires are no longer made. I have found a 295/40/20 rear and 225/45/17 in the same tire model.

Real traditional guys would only use 15 inch wheels (no thanks).

[Davew70]

You make a good point.

[NAZ]

I used the traditional American hot rod approach. 26" M/T skinnys on the front and 29"x16"x15" DOT M/T street slicks on the rear with a lot of rake and the old school altered look. I used 15" rims on the back with the big Wilwood brakes -- yes you can have old school 15" wheels with modern brakes.