Will 235/40 18's work?
 

I'm still looking at getting some winter or all season tires for my 8. Its currently on a boat to Germany. I'm pretty sure that the weather is alot worse than the panhandle of Florida. I'm looking at the continental or pirelli tires in the 235/40 18 size. I've tried the search and couldn't seem to find anything. Any help would be appreciated.Thanks

well 245/40 18s work according to several people so I don't see why 235 wouldn't, also i remember some people who bought winter tires had 235s, presumably on the stock wheels but perhaps not.

Will 235 width winter tires work? Yes. Will they work as well in winter conditions as a 225 or 215? NO. It's undisputable that narrower tires are better for snow and ice traction. That's one of the reasons I went to 17" wheels for the winter setup - the availability of 215/55-17 winter tires. Canzoomer went for 205/50-17s, deliberately sacrificing a small amount of ground clearance, for the even narrower size.

If you can buy 225 width rather than 235 for winter use - you should.

Here's a winter tire sizing article from Tire Rack's tech center.

Regards,
Gordon

They will work but they will be significantly shorter.

the following info shows the difference

225/45WR18 and 235/40WR18 respectivly:

Section Width: 8.85 in 225 mm / 9.25 in 235 mm

Rim Diameter: 18 in 457.2 mm / 18 in 457.2 mm

Rim Width Range: 7 - 8.5 in / 8 - 9.5 in

Overall Diameter: 25.97 in 659.63 mm / 25.40 in 645.16 mm

Sidewall Height: 3.98 in 101.09 mm / 3.70 in 93.98 mm

Radius: 12.98 in 329.69 mm / 12.70 in 322.58 mm

Circumference: 81.58 in 2072.1 mm / 79.79 in 2026.6 mm

Revs per Mile: 800.9 / 818.8

Speedometer1: 60 mph 100 km/h

Speedometer2: 61.34 mph 102. km/h

Speedometer Difference: 2.234% too fast

Diameter Difference: 2.2%

You should be alright as you want to keep any difference to <3%

Try a 245/40WR18 as this will put you at only a 1% difference.

Here is a pic of the Sumitomo HTR+ in 245/40WR18's on my 8. I think they are just perfect!

http://images3.fotki.com/v25/photos/...MG_2985-vi.jpg

I can't tell you whether the size you mentioned work, but I brought my car here (Germany) from Florida and got Dunlop Winter Sport M3s 225/45/18 and they're really incredible. If you're military (or have access to the PX) they can get you the tires. Hope this helps

Hmmm.....well I'm kinda looking for something all season and the 245/40/18's look like a good choice to me. From what Gordon said, it makes sense to go with a narrower tire for the winter but, I'd like to have something that I can run all year round. Autobahn RX8...I'm in the military as well and I shipped my 8 early in Jan. I actually leave the country this Monday 2 Feb. They have my delivery date as 2 Mar 04 but, I think it will be there a bit sooner than that. Its already been three weeks since I've shipped it.

I'm hoping to avoid most of the bad weather when my 8 gets there so thats why I'm looking at the all season tires. That way next year when the bad weather sinks in, I'll have some time to put some money away if I need to get strictly winter tires. Then I can order those Dunlop M3s through AAFES.

Rotary Nut, thanks for posting the differences in the tires for me. It makes alot of sense to go with the 245's instead of the 235's. So there should be no clearance or rubbing problems when you turn with this size tire if its only a 1% difference right? Thanks for all the input.

No rubbing at all! Where in Germany are you going? I spent 7.5 years there and loved being able to drive 120 mph EVERY DAY going back and forth to work from Pioneer kaserne to Fliegerhorst kaserne in Hanau. I envy you dude! Have fun and good luck!

I was looking at the Sumitomo HTR + 245/40/18 but I noticed those also come in 225/40/18. Can I assume those would work fine also? The 225 matches the stock tires, so I would assume so.

I wouldn't do it as it exceeds the 3% difference. It works out to a 3.43% difference and will affect your speedo and engine calibrations.

225/45WR18 vs. 225/40WR18 respectivly:

Section Width: 8.85 in

Rim Diameter: 18 in

Rim Width Range: 7 - 8.5 in vs. 7.5 - 9 in

Overall Diameter: 25.97 in vs. 25.08 in

Sidewall Height: 3.98 in vs. 3.54 in

Radius: 12.98 in vs. 12.54 in

Circumference: 81.58 vs. 78.79

Revs per Mile: 800.9 vs. 829.3

Speedometer1: 60 mph / 100 km/h

Speedometer2: 62.1 mph / 103. km/h

I'll be at Ramstein. So far I know that autobahnRX8 is at Heidelberg and RX8freek is at Spangdahlem. From what my sponsor tells me...he has yet to see and 8 in Germany yet. The were supposed to get one in Landstuhl and the German Mazda Dealership but, they have not received one yet.
From what RX8freek tells me, he's gotten the top speed up to 149, then with the canzoomer stage 1 mod he can hit 157. So the mod does make a difference.

I was in Germany from 98-2000 so this is my second time going back. You can say that I'm pretty excited about it.