Toyo Tires has proven performance credentials. It manufactures the spec tires for the SPEED World Challenge, Proxes T1-S in Touring and Proxes RA-1 in the GT Class, both of which will be on Proxes RA-1 for 2004. Toyo is also the official tire of the NHRA Summit Sport Compact Drag Racing series.
Thus, we were excited when Toyo announced an all-new performance tire, the Proxes 4. It's an all-season, high-performance tire aimed at plus-fitment applications on sport compact cars, sports sedans and coupes.
The internal construction is very similar to that of the Proxes T1-S, which has shown its performance capabilities in SPEED World Challenge. It starts with a jointless bead wire and uses a hard bead filler compound in the sidewall for lateral stiffness. The casing is polyester, followed by two full-width steel belts and jointless edge and cap plies. The latter consist of a continuous length of nylon cord tape to improve uniformity.
The tread design was styled to be attractive as well as functional. It has a solid center rib for stability and steering response. Shoulder tread blocks are paired to support each other and better withstand cornering and braking forces. Tread blocks use a multi-wave sipe, with a zig-zag pattern rather than a smooth channel. Under load, the sipes interlock, allowing the tread blocks to support each other. The result is less deformation and heating of the compound and greater durability.
Wet performance is obtained through a W-shaped tread pattern and "Generation S" silica compound. Computer simulation was used to determine the optimum balance between water evacuation capability and remaining tread surface area in contact with the pavement. Silica compounds have better wet traction and longer life than pure carbon compounds. The paired shoulder blocks and multi-wave sipes also reduce tread deformation when rolling straight, enhancing tire life.
The Proxes 4's UTQG tread wear rating is 300. It has M+S designation, but that's basically a measure of void ratio, not of design for mud and snow conditions. Sizes range from 195/50-15 to 245/35-19. Speed ratings are V (up to 149 mph) for smaller sizes and W (up to 168 mph) for all 17- to 19-inch sizes.
After a tech briefing, we sampled the tire on the Streets of Willow Springs in the previous-generation Toyota Pro/Celebrity Race Celicas. My inner tire nerd interpreted the presentation as, "It's a lot like a T1-S, but with a new, higher-tech tread pattern and a lower-temperature compound." It will work better than the T1-S if there's an inch of snow on the ground, or if it's really cold out, but it probably won't be able to sustain the same dry performance for any length of time.
Driving the Proxes 4 on the track supported that analysis. It had no bad habits and was entirely predictable in its responses. I had the confidence to begin experimenting with left-foot braking. The tires didn't like being pushed as hard as our presence on a race track suggested and eventually overheated and lost grip. After pulling into the pits to put some distance between myself and slower traffic, the grip returned, but only for another lap or so, then the tires were again too hot to work at their potential. Even when hot, however, while not as sticky, the tires stayed consistent. It wasn't as if the tires got hot and the car became undriveable. We're also impressed with the way the Proxes 4 took the abuse. At the end of the hard day of driving, they looked remarkably good. No tire changes for the drive home would have been necessary.
Toyo's target market of enthusiasts, show car owners and entry-level performance car drivers will probably be very pleased with the styling, performance and affordable price of the Proxes 4.
Things We Like About The Toyo Proxes 4:* Predictable handling* Affordable price* Good-looking tread and sideway* Wear-resistant
Things We Don't Like About The Toyo Proxes 4:* Overheats when driven race-track hard