So this glut of 305mm PWC tires seems to be hitting the Mustang crowd lately at cheap prices. I wanted to share this experience as a possible warning - I bought two pallets of new/sticker sets of Conti DP slicks in a similar size in 2014. The results were surprising...
I was so happy! I think I paid like $100/each for NEW slicks, so I thought I had hit the Lotto. I was set for tires for like 2 seasons! These were affordable, brand new, and in a fairly wide 305/650/18 size. The street tire I was running at the time was a 275/40/17 on an 18x10" wheel, and as you can see below these 305s dwarfed those...
Height was initially a concern, as these 650mm tire heights were on the short end of the spectrum of what fits an S197/S550. But when you do the math the 650 mm height translates to 25.5" tall, which is almost exactly the same as a 315/30/18, which we ran in Hoosier DOT flavors for many years... works well on a lowered S197 race car.
We tried these 295/40/18 Hoosiers as well - and even though they were close to the OEM tire heights, they ended up being VERY tall for a race tire (and much slower than thee 315/30/18 in back-to-back test). So the 25.5" tall tires are what we mostly ran on our S197 for 4 out of 5 seasons.
We tried mounting the 305mm Conti slicks onto an 18x10" wheel (above right) and it was a
very poor fit. The same tire mounted to an 18x11 wheel (above left) worked much better.
Above this is the same 305mm Conti slick mounted to an 11" wide wheel (left) and 10" wide wheel (right). The 10" wheel
squeezed the tire BADLY and was too narrow for proper track use. The outer 1/2" of tread on each side wouldn't touch the ground. Wasted tire. So my point is -
only use on an 11" wide wheel (or wider) with these tires.
We ran these at an HPDE test event at Texas World Speedway on March 29, 2014, using our 2011 GT / NASA TT3 car which was coming along in its development (had won all of the TT3 events in 2013-2014 to that point). We had set the TT3 track record there the September before so we had a good baseline to work from. The temps were good at this March 2014 event, too.
By that time we had 2 seasons of testing with this car at this track on DOT 315/30/18 Hoosier A6 tires and my previous best in this car here was in September 2013 at a 1:50.675 lap (TT3 record). I was hoping these cheap Conti slicks I got on close-out would be comparable,
maybe even faster? I mean, damn... these are REAL SLICKS, right?
Amy drove the Mustang at this TWS event for two days (about 3.5 hours worth) of light HPDE use, running some low 1:59s. I took one session (3 lap stint) each day, and Mike Patterson (AI racer that usually wins all of the races in Texas) took some laps Sunday. I managed a best of a 1:56.2 lap. That meant that these 305/650/18 Continental DP slicks were
5.5 seconds slower than the 315 Hoosier A6. And the all four tires were corded at the end of the weekend.
We didn't run this TWS CCW configuration again until April 25-26, 2015. At that NASA race weekend I ran a 1:49.926, resetting the TT3 track record both days (not one of my better showings, but a win is a win). This was on a 335F/345R Hoosier A7 - again, a DOT rated tire. We would typically run these Hoosier A7s for multiple weekends with 2 drivers without cording.
So my impressions of these Daytona Prototype tires was:
they were garbage, and I dumped the rest of the new Conti tires I had, for a loss. Sure, they have shiny letters on the sidewall and are used "on real race cars" but that doesn't mean they still don't suck on 3800 pound pony cars.
Your result may vary. These PWC tires are likely different, but I'd still bet money they are slower than a 315 DOT Hoosier.
Cheers,