[mrrippey]

Running stock 19” wheels and found a pair of 295/35/19 tires for rear. An inch wider than stock but otherwise very close to in terms of difference. Besides the speedo being off slightly, is there any other adverse effects?

Rippey

 

[BlueNorther]

Stock is 265/40 ZR 19 right? So don't you mean 1" wider tread width? Will they even fit on the stock wheels?
Speedo will only be affected by total diameter of wheel plus sidewall height. Tirerack has a calculator to check how much a difference it will be, I'd bet small. An inch would be huge.
Why don't you just go with stock set up?

 

[mrrippey]

I just happened to find a deal is the only reason. The tire technically should fit the wheel, well at least the online calculators state that it would. I really don’t know much about wheels and tires hence why I’m asking. Yes stock is 265/40/19 on 10’’ Wide wheels

Rippey

 

[GregW]

It's not just the wheels that the tyres have to fit.
They have to fit in the wheel wells, not rub on brake lines etc., and suit the suspension.
I have read that many who race 718s and use wider wheels also fit wheel spacers.

 

[mrrippey]

Something I found, maybe 295 wide is a bit too wide

 

[Jim137a]

Are the 295 / 35 / 19 Tires the same brand and model as as the existing front tires. If they don’t match it’s not a good idea to mix and match tires - meaning you should be running one brand and model of tire on all 4 corners.

 

[iliveoncaffiene]

Something I found, maybe 295 wide is a bit too wide

The part you'd have to worry about with the rears is when the suspension bottoms out, will the tire hit the side of the wheel well? Take a tape measure or stick or something and put it against the side of your current rears up into the wheel well. Now move that stick (ruler, tape measure whatever) out a half an inch - does it hit anything or is the wheel well the same height? Do the same for the inner side of the wheel.

You can probably get away with this when you're on a smooth surface (a track) because the suspension will rarely be bottoming out or hitting bumps - but on everyday roads you'd have to account for those things.

 

[Whiteball]

what tire brand? For example, if you look on tirerack for MSC2 295/30/20, they will tell you the min and max wheel width. I believe for 295/30/20 they recommend 10.5" - 11.5" wheel (check to confirm this). 11" being the best fit. 9.5" was stock on 981 Boxster and that is too small. Even if you could find a shop to try to fit the tire, it would not perform properly, and probably would not be safe. I have not checked on the stock 718 Boxster wheel sizes, which I assume you are asking about.
Should you go to a wider tire? Depends on your driving style, goals, etc. Depends on your suspension, wheels, brakes, etc. Lots to consider. It's a slippery slope, so don't just do it because you found a good deal on a few tires.

 

[mrrippey]

I’m going to pass, I’ll stick to stock or recommend fittings. Not trying to mess up my new ride.

Thanks All. I really appreciate your assistance.

Rippey