Why go from 17” wheels to 18”?

[cantdrv55]

Originally Posted by NewArt

I run 235/40/18s on the front from Costco. They weren’t listed on their site but I could order them at the store. I won’t let them mount them though.

Thanks for the info!

[PaulE]

I’ve got a set of 17” Boxster II wheels I bought and the 18” Lt Alloy Carrera wheels the car came with. With OEM Pilot Sport N3 tires mounted the front 17 and 18”s weigh the same. The 18 inch rears weigh less than 2 lbs more than the 17’s. Every lb counts with unsprung weight but gaining an inch diameter in rim is offset by losing a half inch of rubber sidewall on both sides of the tire. For street driving there is no difference but an extra half inch of sidewall to protect your rims from potholes is nice. On the 18’s I just replaced the tires with Pilot Sport 4S tires bought at Costco and mounted by them on my refinished wheels. They do a great job at Costco and with the deal they had on Michelin’s last June, similar to their current Bridgestone deal, I was out the door for less than just buying the tires from Tire Rack. Costco is the only tire place I’ve seen that gives you nitrogen for no charge and religiously uses a torque wrench for the final tightening. YMMV.

[JayG]

If you are buying Bridgestione tires, get the best price you can from COSTCO, or online and then go to a Firestone store. They will match the price and if you use a Firestone credit card, you get an additional 5% off.

Another place for a deal is Summit Racing. They will beat any verifiable priced. IIRC, they often have free shipping as well. I have played that game with them several times on brake pads and otherr parts. My last set of Nt-01's too came from them. I found my tire size mispriced on Amazon and Summit beat it by a buck and I got them in 2 days

[Boxstard]

Originally Posted by PaulE

I’ve got a set of 17” Boxster II wheels I bought and the 18” Lt Alloy Carrera wheels the car came with. With OEM Pilot Sport N3 tires mounted the front 17 and 18”s weigh the same. The 18 inch rears weigh less than 2 lbs more than the 17’s. Every lb counts with unsprung weight but gaining an inch diameter in rim is offset by losing a half inch of rubber sidewall on both sides of the tire. For street driving there is no difference but an extra half inch of sidewall to protect your rims from potholes is nice. On the 18’s I just replaced the tires with Pilot Sport 4S tires bought at Costco and mounted by them on my refinished wheels. They do a great job at Costco and with the deal they had on Michelin’s last June, similar to their current Bridgestone deal, I was out the door for less than just buying the tires from Tire Rack. Costco is the only tire place I’ve seen that gives you nitrogen for no charge and religiously uses a torque wrench for the final tightening. YMMV.

Okay, I stand corrected... 18" light Carrera wheel is well, light as 17". But for most cases going bigger results in heavier.

Anyway factory does not recommend 18" wheels for 1997, keeping my options plain and simple.....

[Anker]

Originally Posted by Blackcloud

But with 18’s you can get Bridgestone RE-71’s on! Not on 17’s.

Yes, you can. Just go with the 225/45-17 instead of the 205/50-17. its 2 cm wider, but fits the rims and doesn't rub. As a bonus you get slightly better grip cornering because of the bigger contact area.

(Edited. the width to sidewall ratios were wrong in the original)