17x7 or 17x7.5, what does 0.5" get or not get me?

[MAT]

I wanted to get a set of 17x7? 42mm offset pro race 1.2 but there?s a long wait. They do have a set of 17x7.5" 45mm offset I can get sooner. What does the 0.5? extra width get, or not get me? Is tire choice an issue? I?m worried about the extra width and offset throwing up rocks on my doors and fenders. I plan to do some autox too so they have to work for that.

 

[CollinMB]

the 17x7.5 will add extra sidewall stiffness on stock width tires. They will also allow you to go with a wider tire as well. There are only benefits, no drawbacks.I'm running 17x8 et35 offset and they still (just) fit under the stock fenders with no rub.

 

[MAT]

I managed to snag a set of 7.5x17 pro race 1.2. Is the stock tire size of 205/40/17 still the way to go for a daily driver?

 

[CollinMB]

I wouldn't go any smaller. I have the stock tires on mine and they're way too stretched. For a 7.5 though they should fit great. Any larger section is going to add cost, I'd say max is probably a 225

 

[dyn085]

I wouldn't go any smaller. I have the stock tires on mine and they're way too stretched. For a 7.5 though they should fit great. Any larger section is going to add cost, I'd say max is probably a 225

^This, and realistically speaking you could choose another 205/40 that isn't so narrow once the OEM are toast. Actual tire sizing isn't regulated very well in the tire industry so there are actually drastic differences between different tires of the same sizing.

 

[MAT]

So how do you figure out sizing then? See my other post on the BFGs. Of the other tires in the stock size they are widest in both tread and section by up to 1" which is hard to believe. I'm not sure they measure that the same way either.

 

[Old Guy]

I am not saying not to go for the 0.5? extra width but the wider wheel will be heavier. The weight is unsprung rotational mass. The OEM wheels are heavy to begin with so you will probably have a benefit with either new wheel.

 

[dyn085]

So how do you figure out sizing then? See my other post on the BFGs. Of the other tires in the stock size they are widest in both tread and section by up to 1" which is hard to believe. I'm not sure they measure that the same way either.

You have to pull up the actual manufacturer specs as they will show you exactly what measurements are taken where. For example, a tire with a 205mm tread can be drastically different from a tire that has a 205mm spacing in sidewall. They will both be listed as 205mm, but one might have a 7" tread whereas the other would be just over 8". A lot of people skip this under the assumption that 205/40 = 205/40, but it's not necessarily true.

As another example, my last set of 215/40 Generals had a tread width that was very near the 235/40 Michelins that I owned on my last car.

 

[pelotonracer2]

I run 215/40-17 Dunlop Direzza DII Star Specs on 17x7.5 inch wide wheels. If I could have gotten away with 17x8s with my current set-up I would have gone that route but I don't think they will fit on a lowered vehicle unless you go with coilovers. The benefit of the wider wheel/tire is better traction, better handling and noticeably improved steering response/feedback (especially at the limits).

 

[pelotonracer2]

I am not saying not to go for the 0.5? extra width but the wider wheel will be heavier. The weight is unsprung rotational mass. The OEM wheels are heavy to begin with so you will probably have a benefit with either new wheel.

Not always. My wheels weigh less than the OEM wheels and are .5 inch wider (around two pounds per corner reduction). Granted the tires might weigh a tad bit more due to the extra width and slightly taller sidewall but it is less than a pound difference per tire with my set-up. It depends on the wheel, materials and manufacturing process. Some aftermarket wheels are heavier. Tire Rack seems to be pretty close on their weights for wheels (I'm on my third set of wheels.. lol).