BRISTOL, Tenn. — The moment practice ended at Bristol Motor Speedway, Kurt Busch climbed the steep banking of the concrete bullring. He checked the track temperature in several spots, then used his shoes to test the grip of the surface as he scuffed his way back down.

There’s a sticky situation heading into Sunday’s race in Thunder Valley, and it’s causing fits for the drivers.

‘‘It’s tough to trust, it’s tough to predict,’’ said Busch, a five-time Bristol winner.

Bristol officials applied a VHT resin to the track surface that is intended to enhance grip. The TrackBite is much wider than it was last summer, when Bristol first tried it in August in an effort to make a stronger second lane. The top lane for years had been the preferred line, but the wider swath of VHT seems to have made the bottom of the track the place to be as drivers used limited practice time to prepare for Sunday’s Food City 500.

Intermittent rain at Bristol has wiped out a ton of the notes drivers have gathered about the surface because every time they think they’ve figured out a lane, the showers wash off any tire rubber that’s been accumulated. The Xfinity Series race, the Fitzgerald Glider Kits 300, was stopped for rain Saturday, hours after the Cup drivers had completed their final practice.

‘‘The surface was real slick and then it was really grippy and then it started to slicken back up,’’ Brad Keselowski said. ‘‘It’s going to be an evolving surface race, so that just means it’s going to be tough. We’re supposed to be the best, so we’ll have to figure it out.

‘‘It’s changing faster than I can keep up with it. This will be a weekend full of things we’ve never seen before, which usually means the field is privy to making a lot of mistakes, a lot of action, a lot of wrecks and that’s not always a bad thing.’’

Seven-time NASCAR champion Jimmie Johnson said the driver’s council met during the fall and was in favor of Bristol continuing to explore using the VHT because ‘‘we were all eager to make sure it was back down and thought that it did offer more options.

‘‘I welcome any change that might be thrown at us and any opportunity to create different lanes and searching around the race track,’’ he said.

Only every time on the track, the bottom lane is where everyone wants to be — all but current points leader Kyle Larson.

Larson, who starts on the pole because Friday qualifying was washed out, was among only a handful of drivers trying to run near the wall during practice. It almost bit him during Saturday morning’s session when he spun and clipped the outside wall. It caused only cosmetic damage to his car.

But, after running a chunk of practice on the bottom line, he went to work on the top and wondered why so few other drivers were willing to try to make it a two-lane track.

‘‘I feel like it would still be really fast up there [in the top lane], it’s just nobody is brave enough to go up there and work in the groove,’’ Larson said. ‘‘The VHT is wider than the width of our race cars now, too, which makes it extremely easy to run around the bottom.’’

Should the top line fail to become appealing by race time, Bristol could revert to the way it once was — a one-lane track in which bumping a car out of the way was the only way to make a pass.

Kyle Busch led the field in Saturday’s final practice. He had two wins at this point of the season last year but has yet to visit victory lane this season.

In fact, all of Joe Gibbs Racing is still seeking its first Cup victory.

Busch led the field with a lap at 128.563 miles per hour and teammate Daniel Suarez was second at 128.262.

Kasey Kahne posted the best 10-lap average at 127.482 m.p.h.

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Erik Jones won his second straight Xfinity Series race after after capturing the Fitzgerald Glider Kits 300 Saturday.

Jones, who also won at Texas Motor Speedway on April 8, was the defending race winner at Bristol from last year.

Ryan Blaney finished second — the same result he’s had in all three Xfinity Series races he’s entered.

‘‘Three seconds this year, so that’s getting old,’’ Blaney said.

Daniel Suarez was third to give the Joe Gibbs Racing cars two spots in the top three. Xfinity Series leader Elliott Sadler was fourth.

Daniel Hemric won a $100,000 bonus from Xfinity as part of its Dash-4-Cash program. He finished fifth.