Need help /o/
I've got 225/45zr17 94w xl tires, and i need to know, if i replace one of them (it's completely bald and I can only afford to replace one right now), does it have to be ZR, or can it be R and there will be no problem?
Thank you for your help
Its not what I'd call dangerous.
Those letters are speed ratings, saying the maximum speed a tyre is designed to run at without shredding itself or having a blowout
What will happen is uneven wear compared to the others, slight pulling to one side during heavier braking if the traction of the tires differ greatly and maybe some slight vibration
R is completely different to ZR. R is a rating of merely 106 mph, Z(R) is a rating in excess of 149 mph. This is not only dangerous, but in some countries can be flat out illegal to mount summer tires that are rated for less than what your car's top speed is.
If he stays below the speed rating there shouldn't be a danger to it, though it won't make it legal if it's illegal in the first place. At least it is here in Germany. Winter tires are excempt because they have lower ratings by nature, you simply mustn't exceed their rating in that case.
In Germany and neighboring countries I can completely understand... not really fun when Akhmed and his four fuckhead buddies pull onto the glorious Autobahn in their W210 E-Class on 10 year old P-rated Nankangs
seriously, low grade tires on bigger rims and wider width from stock doesn't gain you any true sport performance. Get something that fits your suspension tune level (stock, lowering springs, coilovers...) and decide how much trust you want to be able to put into your tires when hauling ass.
I run the same tire size as OP on my coilover'ed s13 240sx. Tried several brands over the years, ~100,000 miles with coilovers on public roads.
Current winner in best tire (not every new set was better than the previous) is the Michelin Pilot Super Sports. Butter smooth ride (for a coiled s13), high speed stability is fantastic (previous tires would shimmy side-to-side and scare the shit out of you), and wet/dry grip is 11/10. 40k mile wear warranty.
I haven't reached the limit of these tires on public roads, it will take a track day to find out. I remember in Best Motoring International the drift king was speaking to other pro drivers about the grip power levels of Sport Summer DOT legal Tires vs racing slicks. They all agreed that at the time (mid 2000s episode) that the DOT legal sport tires where equivalent to racing slicks of the 1990s. So in theory street tires are reaching the levels of early 2000 racing slicks today. Either way, the power levels of modern sport tires are reaching what I call "unlimited street-able grip" as in: to reach the limit of these tires you would have to be traveling at a greatly unsafe speed on a public road.
There is no escape area for most public roads, trees will fuck you up, a sand trap at a track might scuff your paint a bit.
Drive carefully my friends.
Nowdays, the "ZR" is redundant, as OP has W rated tires. "R" only designates it's a radial tire, it's not a speed rating.
OP will be perfectly fine with R17, as long as they're also W rated (given this is the stock speed rating) and proper load rating.