Pirelli believes rain in Formula 1's German Grand Prix will be a step into the unknown as its 2019 wet and intermediate tyres have not run on track this year.
Heavy rain caused a red flag in the Porsche Supercup race on Sunday before the rain eased up, although it is expected to return in the hour before the race at Hockenheim.
Both the wet and intermediate have changed for this year relative to 2018 due to new compounds.
The tyres were developed last season over three tests on artificially soaked tracks, with Ferrari conducting running at Fiorano in April, while Mercedes tested at Paul Ricard in May before McLaren and Red Bull tested at the same circuit in September.
"It will be interesting if we have a wet track because nobody tested the wet and intermediate before," said Pirelli F1 boss Mario Isola.
"We just have data coming from the tyre tests, but nothing coming from a race weekend. We had a few laps on intermediates, but nothing representative of proper wet conditions.
"They are different from 2018 because last year we had two compounds for intermediates, and two compounds and for wets.
"One was for cold conditions and low severity circuits, the other one was for higher roughness and more severe circuits. This year we have just one.
"With the new product the wet is a new compound, and also a different profile, and the intermediate is a different compound. Both are suitable for different conditions.
"This is to make life easier for the teams, because, with two compounds and not a lot of testing, it was really difficult to understand the performance of the two compounds.
"But it's also true that they have not tested them before. So there is a bit of unknown going into the wet conditions."
Max Verstappen, Charles Leclerc and Sebastian Vettel will have some extra experience as the only drivers to have driven their 2019 F1 car on any form of the wet tyre.
But they will not have been told the exact specification of the tyre and if the compound they used or identical or similar to the 2019 product.
The other drivers on the F1 grid have no experience with the current tyres because there have been no wet test sessions or race weekends.
But Norris, who ran the 2019 prototypes on last year's McLaren at Paul Ricard, says he still has a lot to learn.
"I don't know what tyres they were and if they are the ones we are running this year," he said when asked by Autosport.
"But I did the Pirelli test last year, obviously was in last year's car not this year's car.
"It is going to be a challenge, not only for ourselves but for learning and to understand how these cars work in the wet."
Romain Grosjean added: "We hope they're not too dissimilar to last year.
"We hope we know where the kind of window is, or the lower part of the window, and we hope we get there. There's not much you can do about the weather, so let's see."